Add disable highlight group and suppress warning options

[DraggonFantasy]

Lua is frequently used as embedded language (for example in games). The applications, that uses Lua, provides some API to it. But of course Lua Inspect doesn't know anything about it, so it thinks that here's some error.

I've added few options to give user more control - first one allows to disable some of highlighting groups without disabling whole highlighting, and second allows to mute some of warning messages using regexps.
Personally I use it to solve the problem I described above (I disable highlighting of undeclared globals + mute warnings about API functions provided by application), but I'm sure there are more uses for that options