Update LineParser about coala HOT 3 CLOSED

I hereby name the
section.key = ...
syntax section override because you temporarily override the section you're in. You can do this for multiple keys too:
[section31]
42.key, 47.key, key = valid everywhere

from coala.

I dont want to make it a Parser derivative because it would have to provide settings then and thats beyond its task of just stripping things and partitioning the string. The abstract things happen in the ConfParser.

from coala.

escape part is covered in #79 so this is a duplicate, closing since section override is implemented on wip/lineparser and ready to review.

from coala.