Improve the scalaExpr parser

[domna]

The current scalaExpr Regex has the form [^%]* and is automatically converted into a parser which is used in the grammer to parse the file into blocks (whether it is a prolog or a scala part). But the problem with this Regex is, that it parses everything but the % character. This was a workaround for me that the Regex stops consuming everything in my file and recognizes the prolog block of the file.
The problem is that if there is any % character (even in strings) in the scala definiton above the prolog block the result is a parser error.

So there must be a way to stop the regex consuming everything and also have the possibility to write every character in the scala def above.