#13 Sub string support for match()

This adds very simple sub string matching for RSL's match() function.
Not sure if this is the proper way to do this or if its compatible with all OS's however its worked good for my shaders on Linux.
This doesn't however add any regular expression matching.

[Anonymous]

[Roine Gustafsson]

I upgraded your patch to regex support. I thought I'd attach it here, but there's no way to attach files to comments :(
I'll upload it later separately with a bunch of other patches.