Freq argument for wavelet-based methods (#580)

* Update tsmodel.py

* replaced freq_mehod by freq

in Series.wavelet() and MultipleSeries.wavelet(). Also cleaned up module imports in core classes

* implemented freq in wavelet_coherence()

with CI tests

* implemented CI test for global_coherence() freq passing

* consolidate coherences

pyleoclim/core/__init__.py

@@ -12,8 +12,7 @@
 from .surrogateseries import SurrogateSeries
 from .ensembleseries import EnsembleSeries
 from .scalograms import Scalogram, MultipleScalogram
-from .coherence import Coherence
-from .globalcoherence import GlobalCoherence
+from .coherences import Coherence, GlobalCoherence
 from .corr import Corr
 from .correns import CorrEns
 from .multivardecomp import MultivariateDecomp

pyleoclim/core/coherence.py

@@ -13,7 +13,7 @@
 from copy import deepcopy
 
 from matplotlib.ticker import ScalarFormatter, FormatStrFormatter
-from matplotlib import cm
+#from matplotlib import cm
 from matplotlib import gridspec
 
 from tqdm import tqdm