new regex based input plugin

added regex input plugin. A more complete offering of what the text plugin currently does.
renamed to regexp_parse.py
changed config format to differ less between flexget (url and title field) and custom fields
added a lot of docstrings and removed special handling code for url and title entry fields
fixed variable name
fixed more issues with changing regex to regexp
removed debugging print
fixed some docstrings and added class docstring
more documenting and added some idea for later work
fixed pep8 errors
Update regexp_parse.py

added some more detail to the description
Merge pull request #40 from tpolich/master

New regex input plugin