Tweaked the inverted colors,shell Makefile

Tweaked the way we handle inverted colors so that documents with no "day" class tag fr their primary stylesheets can revert back to these stylesheets when prompted, the inverted colors run into problems on document reload, this needs to be fixed.

Other than that I removed the webkit flags and libs from shell/Makefile.am , they were there because at a very early stage of the project I had decided to use a webkit_web_view directly, then I ended up extending and using it in libview.