Allow docstrings to happen anywhere in the code

In Python docstring can happen just in the middle of the code, e.g.
documentation for class or instance variables. So let's fold them.
This also removes assumption that any string ending with '):' is an end
for def: or class: (it can by if: or anything else).
Merge pull request #18 from YorikSar/docstring_everywhere

Allow docstrings to happen anywhere in the code