Implement various unicode support related updates.
Update various docstrings.
Update system encoding manipulation.
Update various docstrings.
Update default test connection ip address in "foundations.common" module.

Closes KelSolaar/sIBL_GUI#191.
Implement fallback mechanism if "foundations.environment.getSystemApplicationDataDirectory" definition doesn't return a valid directory.

Closes KelSolaar/sIBL_GUI#192.
Remove debug test in "foundations.environment.getUserApplicationDataDirectory" definition.
Update "foundations.environment.getUserApplicationDataDirectory" definition.
Ensure "foundations.parsers.SectionsFileParser" parser handle empty attributes.
Ensure cache is empty before writing in "foundations.parsers.SectionsFileParser.write" method.
Update "foundations.common.isInternetAvailable" definition.
Add various new internet connection test addresses in "foundation.common" module.
Update 'foundations.core.exit' erroneous default argument.
Change copyrights dates.
Update class objects docstrings.
Update definitions and methods docstrings.
Update decorators docstrings.
Merge branch 'feature/v2.1.0' into develop

Conflicts:
	foundations/common.py
	foundations/decorators.py
	foundations/exceptions.py
	foundations/io.py
	foundations/parsers.py
	utilities/getSphinxDocumentationApi.py
	utilities/getSphinxDocumentationTocTree.py
	utilities/reStructuredTextToHtml.py
	utilities/sliceDocumentation.py