Processes
ASTNull nodes in query models. Null's that appear in
projections are simply removed as that doesn't change the semantics. Null's
that appear in value comparisons are either replaced with
ASTBound nodes or constants.
author: Arjohn Kampman
Processes escape sequences in ASTString objects.
Parameters: qc - The query that needs to be processed. throws: MalformedQueryException - If an invalid escape sequence was found.