[TxMt] Restrict characters in multiline strings

[Jacob Carlborg]

To create a pattern in a TextMate grammar that matches across multiple 
lines the "begin" and "end" keys are necessary. But is it possible to 
somehow restrict what is matched between the begin and the end?

I'm trying to create a pattern for the hex string literal in D. It's 
like a regular string literal but can only contain hex characters.

-- 
/Jacob Carlborg