Point cloud related conda recipes

Work in progress to build conda packages for pdal and dependencies

Trying it out

conda install -c mathieu pdal

or using an environemnt specification by creating an environment.yml file as follows:

# environment.yml

name: pdal-env
channels:
  - mathieu
  - conda-forge
dependencies:
  - python=3.6
  - pdal

and run conda env create -f environment.yml