add ionex.py with simplified IONEX file reading

+ add mintpy.objects.ionex sub-module to handle all the IONEX file download/reading
   - add ionex.py based on daniestevez notebook, to simplify the IONEX file reading
   - move the following functions from mintpy.simulation.iono, to be more independent:
       - dload_ionex()
       - get_ionex_value()
       - get_ionex_filename()
       - get_ionex_date()
       - get_ionex_height()
       - plot_ionex()
   - simulation.iono.py: remove the obsolete read_ionex_tec()

+ add unit test for objects/ionext.py:
   - add tests/objects/ionex.py
   - add tests/data/jplg3190.15i
   - update .circleci/config.yml

+ update simulation.iono.py and iono_tec.py accordingly

+ update docs:
   - add ionex to docs/api/module_hierarchy.md
   - update .gitignore against the latest github example for python

.circleci/config.yml

@@ -50,6 +50,7 @@ jobs:
           command: |
             export PATH=${CONDA_PREFIX}/bin:${PATH}
             ${MINTPY_HOME}/tests/test_asc_desc2horz_vert.py
+            ${MINTPY_HOME}/tests/objects/ionex.py
 
       - run:
           name: Testing MintPy on Example Dataset 1/4 - FernandinaSenDT128 (ISCE/topsStack)

.gitignore

@@ -1,15 +1,134 @@
 *.DS_Store
 *.pyc
 *.idea/*
-*ipynb_checkpoints*
-*.egg*
+isce.log
+
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
 build/
+develop-eggs/
 dist/
-docs/api_docs/
-docs/resources/*logo*
-docs/resources/*.ai
-docs/resources/*.pdf
-docs/deps.svg
-isce.log
-mintpy/modis*
-site/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+pip-wheel-metadata/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+.pytest_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+.python-version
+
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don't work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow
+__pypackages__/
+
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/

docs/api/module_hierarchy.md

@@ -9,6 +9,7 @@ Hierarchy of sub-modules within MintPy. Level _N_ modules depends on level _N-1_
     /objects
         cluster
         colors
+        constants
         giant
         ramp
         sensor
@@ -18,50 +19,50 @@ Hierarchy of sub-modules within MintPy. Level _N_ modules depends on level _N-1_
             l1regls
             lstl1
         arg_group
-        constants
-        ptime
+        map
+        ptime (including progress)
         utils0
     /simulation
         fractal
 ------------------ level 1 --------------------
     /objects
         conncomp      (objects/ramp)
+        ionex         (objects/ptime, utils/map)
         stack         (utils/ptime)
     /utils
         time_func     (utils/ptime)
-        map           (utils/utils0)
     /simulation
         decorrelation (utils/ptime)
         defo_model    (utils/utils0)
         variance      (utils/ptime)
 ------------------ level 2 --------------------
     /utils
-        readfile      (utils/{ptime, utils0}, objects/{stack, giant, sensor})
-        s1_utils      (utils/{ptime, time_func}, objects/{stack})
+        readfile      (objects/{stack, giant, sensor}, utils/{ptime, utils0})
+        s1_utils      (objects/{stack}, utils/{ptime, time_func})
 ------------------ level 3 --------------------
     /objects
-        resample      (utils/{utils0, ptime,  readfile})
+        resample      (utils/{utils0, ptime, readfile})
         coord         (utils/{utils0, utils1, readfile})
     /simulation
-        iono          (utils/{utils0, ptime,  readfile})
+        iono          (utils/{utils0, readfile})
     /utils
         writefile     (utils/{readfile})
         network       (objects/{stack, sensor}, utils/{readfile})
 ------------------ level 4 --------------------
     /objects
-        gps           (objects/{stack, coord},  utils/{ptime, utils1, readfile})
-        stackDict     (objects/{stack},         utils/{ptime, utils0, readfile})
+        gps           (objects/{stack, coord}, utils/{ptime, utils1, readfile})
+        stackDict     (objects/{stack}, utils/{ptime, utils0, readfile})
     /simulation
-        simulation    (objects/{stack},         utils/{ptime, network}, simulation/{fractal, decorrelation, defo_model})
+        simulation    (objects/{stack}, utils/{ptime, network}, simulation/{fractal, decorrelation, defo_model})
     /utils
-        attribute     (objects/{coord},         utils/{readfile})
-        utils1        (objects/{stack, ramp},   utils/{ptime, utils0, readfile, writefile})
+        attribute     (objects/{coord}, utils/{readfile})
+        utils1        (objects/{stack, ramp}, utils/{ptime, utils0, readfile, writefile})
 ------------------ level 5 --------------------
     /utils
-        plot          (objects/{stack, coord, colors},  utils/{ptime, utils0, readfile, network, map})
-        utils         (objects/{stack, coord},          utils/{ptime, utils1, readfile})
+        plot          (objects/{stack, coord, colors}, utils/{ptime, utils0, readfile, network, map})
+        utils         (objects/{stack, coord}, utils/{ptime, utils1, readfile})
         isce_utils    (utils/{ptime, readfile, writefile, utils1})
 ------------------ level 6 --------------------
     /objects
-        insar_vs_gps  (objects/{stack, giant},          utils/{readfile, gps, plot, utils})
+        insar_vs_gps  (objects/{stack, giant}, utils/{readfile, gps, plot, utils})
 ```