Non-ASCII-Character Treatment

At least in grammars, some characters are not treated correctly.

In Java, all characters are allowed https://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-IdentifierChars

• check support and create issue in https://git-st.inf.tu-dresden.de/jastadd/relational-rags
• check support and (if needed) create issue in https://bitbucket.org/jastadd/jastadd2/
• fix lexer in plugin