Doc decorator

In preparation of #109 (closed) and #236 (closed) the documentation pipeline had to be changed from code-parsing to decorator based docstring assignments (to the sac.SaQC methods). Also, this change makes it much less hacky and transparent and generates a central place for templating saqc-(method)-docstrings (sphinxdoc/scripts/templates.py)

MR includes:

• new file sphinxdoc/scripts/templates.py, containing:
  • helper functions for docstring modification (add/remove sections/parameters)
  • doc decorator for object documentation
• saqc.SaQC methods are now decorated with doc decorator
• Returns section of methods documentations now lists saqc.SaQC object defaultly (saqc methods template)
• removal of hacky workaround scripts

The MR aims to preserve appearence of documentation as it is, by removing inner workarounds and generating template modification mechanism for future modifications (for example according to #236 (closed)