Improve CharStreamScanner

[hohwille]

Now that CharStreamScanner is really cool new demands arise. We want to do some further improvements:

• add simple method variants with defaults for optional args (e.g. add expect(String) that delegates to expect(string, false)).
• extend readUntil method variants for more complex parsing
• add readJavaStringLiteral() method that can parse a string literal according to JLS.
• therefore also extend StringUtil with resolveEscape methods that be be reused.
• extend CharFilter with constants like HEX_DIGIT_FILTER, etc.

[hohwille]

For the record: The change in AbstractNlsFormatterManager was done because whilst testing a temporary error was caused during creation of an exception causing wired effects when another NLS exception was created in catch block.

[hohwille]

Done and merged.

[hohwille]

Finalized and merged.