Reviewed-by: Leena Miettinen

The Parentheses, TextBlockUserData and TextEditDocumentLayout classes
and their member function implementations were spread around the
BaseTextEditor class. Moving them to their own file to make the code a
bit better organized.

Reviewed-by: mae

Reviewed-by: Thorbjørn Lindeijer

Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>

There's no need to reparse something we already got the AST of.

Reviewed-by: Erik Verbruggen

a op b -> !(a invop b)
and
a op b -> b flipop a

Reviewed-By: Christian Kamm <christian.d.kamm@nokia.com>

Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>

Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>