Feature CORE-4403 - Allow referencing cursors as record variables in PSQL.
Improvement CORE-4434 - Extend the use of colon prefix for read/assignment OLD/NEW fields and assignment to variables.

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/trunk@59606 65644016-39b1-43b1-bf79-96bc8fe82c15