Solve Windows bugs and CI

[enekomartinmartinez]

@JamesPHoughton this is ready for merge.

Some bugs were detected and solved for Windows:

• encoding missing when loading submodules was giving an error.
• the path of Macro objects was hardcoded from the root, this was making the models crash in Windows and would return an error if the model folder path is changed.

Improvements:

• Enable using encoding information for reading Vensim model files.
• Read modules files with "UTF-8" encoding.
• Correct the paths and use pathlib.Path type object in the model file for external objects, modules and Macros.
• Correct several tests to make them run on Windows also.
• Skip some test on windows (invalid escape sequence error and CLI) to be corrected or replaced in the future.
• Add windows to GitHub Actions CI.
• Solve issue Circular reference error in models with ACTIVE INITIAL #305 of dependencies with active initial objects.

Closes #303 #305

[coveralls]

Coverage increased (+0.001%) to 99.81% when pulling 6cc60ed on enekomartinmartinez:encoding-files into 54fa0f1 on JamesPHoughton:master.

[pep8speaks]

Hello @enekomartinmartinez! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file tests/integration_test_vensim_pathway.py:

Line 28:80: E501 line too long (105 > 79 characters)

Comment last updated at 2021-12-16 17:27:27 UTC

[enekomartinmartinez]

PR update with the solution for #305 adding running a new test model from test-models repo.
@JamesPHoughton

[JamesPHoughton]

Looks good to me. =)