#124 support for multiple lexers

[PatL]

Although SQLLexx is fine for oracle and mysql, it doesn't support sybase. the database adapter should be able to return a database specific implementation of the lexer.
As the parse method of SQLLexx is static, it can't be overriden. By making it non-static, the database adapter's getLexer can return the correct lexer.
Patch replacing the lexer and fixing all the calls to parse attached.

[PatL]