Fix color resetting in plugins

Remove defaulting in highlighters, which isn't needed, and was setting
the wrong thing anyway.  Also a little new hightlighter
also use munged RPC name in URL - as that's what the stock javescript does (as far as I can tell - it's stopped returning this munged version for now)
for #552
Merge pull request #553 from vita10gy/highlighter_fix

Fix color resetting in plugins