[Offgridders V4.6.1] - RTD and Installation fix

[Offgridders V4.6.1] - 2020-11-07

Added

• Docstrings to A1, B, C, D0, D1, E, F, G0-2 (#131, #132, #133, #134, #135, #136)
• Literature file to readthedocs (#129)
• Added some docstrings to functions in G2a, copied from Components.rst (#125)
• Replaced "Yes" and "No" with True and False. In H0 and inside the Excel Files (#127)

Changed

• Update README (#129)
• Bump black version number (#144)
• Devided the requirements.txt into a base one (users) and an extended one for developers and for troubleshooting (requirements_dev.txt) (#145)
• Updated the installation instructions in Readme.md and of the RTD (#145)

Fixed

• Small content corrections to readthedocs (#119,#123,#125)
• Fixed parsing issue with evaluation_prespective by fixing definition of logging message and constant varibale definition of AC_SYSTEM (#143)