.xql overhaul:
- removed misleading sql-statements from db_* calls, which were
ignored due .xql files
- removed bug where same query name was used in a single proc
with different intended sql queries, but the same was picked
up from the .xql file due to the name
- removed multiple entries of same query name from .xql files
(e.g. the entry "package_create_attribute_list.select_type_info" was
7 (!!!) times in a single .xql file)
- removed redundant queries for unsupported versions of the dbms
- added missing xql entries for db-backends, where other db-specific
queries exists (e.g. added an entry to -oracle.xql, where an entry
existed in -postgres.xql)
