add support for Custom Tags/Categories and Custom Screenshot Previews.

i know this is an old request, but i still feel its valid still after so long.
so be able to add simple tags and categories that can be used by the group 
filter system and search bar aswell.

also the screenshot previews, cant there be a way for us to use the preview 
thumbnails that windows is already generating for our files and use that 
instead of the 404 picture when there is no screenshots on TVDB or heck, if the 
series dont have TVDB support at all. this will work great with Movies as many 
are NOT in TVDB in any shape or form aswell as H-content witch get banned on 
TVDB even tho there is nothing bad that gets added to their entries.

those two are really big gripes for me atleast.
its just too bad this will never get updated as the project have died off it 
seems..... :/ 
wish you guys where back at working and supporting this great app.

Original issue reported on code.google.com by Are.Fins...@gmail.com on 5 Jul 2014 at 2:53

jon1caleb2 / jmm

add support for Custom Tags/Categories and Custom Screenshot Previews. #526