started to create docs with sphinx...
finished provisional docs

Didn't document TODAY and ENDIAN yet.
Also there are some questionable things about the docs:
* is the figures-param understandable?
* is there an alternative to the sphinx-style class- and
function-docstrings?
* reworking the docstrings of the parser-functions (maybe some more
over them in the concept-section)
* reworking the docstring of parsetimedelta
finished docs for now.
removed docs/_build/* from the repo;

...and bugfix some sphinx-syntax in the parser-functions-docstrings.
reworking parsetimedelta-docstring