Optional newline handling in MVEL parser

MVEL parser explicitly handles newlines so that statements can be terminated automatically without semicolons.

However, in some situations this is not necessary. For instance, while parsing constraints, newlines should be treated as non-significant whitespace.

We add support to a new lexer state, that can be switched at run-time (parser instantiation time), to allow for whitespace to be fully ignored, newlines included.