Add support for pathlib.Path objects as input

[remtav]

Description

Add support for pathlib.Path objects

Fixes #459

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected - these changes will not be merged until major releases!)

How Has This Been Tested?

Please describe tests that you added to the pytest codebase (if applicable).

3 very simple tests have been added to test the core input reading function for vector and raster files. These tests make sure a pathlib.Path object pointing to a file are succesfully read by the different utilities.

Checklist:

• My PR has a descriptive title
• My code follows PEP8
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new errors
• I have added tests that prove my fix is effective or that my feature works
• My PR passes Travis CI tests
• My PR does not reduce coverage in Codecov

If your PR does not fulfill all of the requirements in the checklist above, that's OK! Just prepend [WIP] to the PR title until they are all satisfied. If you need help, @-mention a maintainer and/or add the Status: Help Needed label.

Copied from #460

[remtav]

@rbavery

CI checks seems to be launched, but unfortunately there is a permission error during tests:

Thanks for your informative e-mail on the current state and envisionned future of solaris by the way.