PR: Add support for Python 3.7

[jnsebgosselin]

Fixes #41

• [x] Add a Python 3.7 Matrix in AppVeyor
• [x] Build Wheels for Python 3.7
• [x] Bulid conda package for Python 3.7
• [x] Update documentation

[jnsebgosselin]

Conda is downgrading Python to 3.6.6 during the conda update -q conda command. So I guess for the moment I'll stick to Python 3.6 and support 3.7 later.

[jnsebgosselin]

Even without executing the conda update -q conda command, Python is being downgraded from 3.7 to 3.6.

[jnsebgosselin]

The problem seems to be with fiona that is not yet supported for Python 3.7 on Win-64 (https://anaconda.org/anaconda/fiona).

So I think there is nothing I can do for the time being, but wait until this is resolved upstream and the package are made available on the defaults channel of anaconda.

It seems like this was fixed upstream already (https://github.com/Toblerity/Fiona/issues/619), so it is only a matter of time until the package are made available on the defaults channel.

[jnsebgosselin]

If I update conda, we get the following error when executing conda-build:

CommandNotFoundError: Your shell has not been properly configured to use 'conda activate'.
If using 'conda activate' from a batch script, change your
invocation to 'CALL conda.bat activate'.
To initialize your shell, run
    $ conda init <SHELL_NAME>
Currently supported shells are:
  - bash
  - cmd.exe
  - fish
  - tcsh
  - xonsh
  - zsh
  - powershell
See 'conda init --help' for more information and options.
IMPORTANT: You may need to close and restart your shell after running 'conda init'.
Traceback (most recent call last):
  File "C:\Miniconda36-x64\Scripts\conda-build-script.py", line 10, in <module>
    sys.exit(main())
  File "C:\Miniconda36-x64\lib\site-packages\conda_build\cli\main_build.py", line 442, in main
    execute(sys.argv[1:])
  File "C:\Miniconda36-x64\lib\site-packages\conda_build\cli\main_build.py", line 433, in execute
    verify=args.verify, variants=args.variants)
  File "C:\Miniconda36-x64\lib\site-packages\conda_build\api.py", line 207, in build
    notest=notest, need_source_download=need_source_download, variants=variants)
  File "C:\Miniconda36-x64\lib\site-packages\conda_build\build.py", line 2300, in build_tree
    notest=notest,
  File "C:\Miniconda36-x64\lib\site-packages\conda_build\build.py", line 1450, in build
    windows.build(m, build_file, stats=build_stats)
  File "C:\Miniconda36-x64\lib\site-packages\conda_build\windows.py", line 326, in build
    check_call_env(cmd, cwd=src_dir, stats=stats, rewrite_stdout_env=rewrite_env)
  File "C:\Miniconda36-x64\lib\site-packages\conda_build\utils.py", line 366, in check_call_env
    return _func_defaulting_env_to_os_environ('call', *popenargs, **kwargs)
  File "C:\Miniconda36-x64\lib\site-packages\conda_build\utils.py", line 346, in _func_defaulting_env_to_os_environ
    raise subprocess.CalledProcessError(proc.returncode, _args)
subprocess.CalledProcessError: Command '['cmd.exe', '/c', 'bld.bat']' returned non-zero exit status 1.
Command exited with code 1

The problem seems very similar to the one reported in https://github.com/conda/conda/issues/7706. The thing is, this issue is supposed to be fixed, so I do not understand why I still get this here.

So to avoid this for the time being, I'll pin conda version to 4.5.*.

[jnsebgosselin]

Ok, so that's it. It was not working because I needed to let conda-build update too, so that it is compatible with the new version of conda in the 4.6.x series.