Removed unnecessary color info hashes

The unused color hashes and settings hashes
have been removed.
Added Features to Passthrough Filter

The passthrough filter now has a fallback option for level
filtering (using a new matcher), and also supports source
filtering
Reworked supports_sev

Reworked the way supports_sev works and retooled the code to actually
respect it.  Now, the filter_sev parameter may be passed to force
enable or disable severity filtering options.  If not present,
the filename will be inspected as previously.
Changed JS Filtering Semantics

JS Filtering now works with server-side filtering properly --
when server-side filtering is enabled, the filter links for
levels below the specified level will be actual links, while
those above will filter dynamically.