F# better typeparam handling

 * Still doesn't handle 'when' or 'static member' constraints.
 * Sample code from Colin's FSharp.Actors project.
Gherkin support

Hacked into shape from this
https://github.com/cucumber/gherkin-syntax-highlighters
Ignore RubyMine cruft
Capture do, end, /^step def text$/
Gherkin test (I think)
Gherkin done
Step Defs

I think this is a bit simplistic, but it works
Add support for dustjs
Add support for interactive ruby sessions (irb)
Merge branch 'master' of github.com:bfui/highlight.js into dust
Add Dust example to test.html, add CSS classes reference
Reintegrate irb definition into the ruby one
Fix broken link to class reference
Add missing change coming from #382
Merge branch 'fix-changes'
Move curlys up to the right side
Fix some highlight clobbering in arta
Remove unneeded use of '*' for comments
One rule per line style for all css

It's better to rely on the compression of css to save space. This is also to
keep the css files similar in style.
Add missing semicolons

Compression also handles removing the last semicolon in a css style block.
It is also easier to add and remove rules if needed.