css: Fix trailing padding on threads

And also fix font display for <pre> sections created from plain/text thread
posts
thread: Display thread meta-data without wrapping?

Change thread entry title bar to use more flexible layout using div's and
span's in hopes of avoiding unnecessary wrapping -- especially in the poster
name column..
Merge pull request #272 from greezybacon/issue/thread-css

thread: Several CSS changes for consistency

Reviewed-By: Peter Rotich <peter@osticket.com>