Fixed:

1. Fixed role disappearing from context variable, after changing role to unexisting

Ported from Firebird:

1. CORE-6000: gbak issues "Your user name and password are not defined" when command switch "-fe(tch_password) ..." is specified when run as service.
2. CORE-6163: Generator pages are not encrypted.
3. Fixed races during attach/detach to the monitoring shared file (similarly to how it was done for other shmem files).
4. CORE-6171: No current record for fetch operation with queries with aggregated subselect