Call GetDateTimeValue for all temporal types on all server versions.

git-svn-id: http://heidisql.googlecode.com/svn/trunk@4797 560a3889-bb33-0410-9f33-43a8a102dc09
Catch date/time conversion errors in GetDateTimeValue, which happen e.g. when passing an empty date.

git-svn-id: http://heidisql.googlecode.com/svn/trunk@4798 560a3889-bb33-0410-9f33-43a8a102dc09
Enable foreign keys editor on NDB cluster >= 7.3.x. See http://www.heidisql.com/forum.php?t=16059

git-svn-id: http://heidisql.googlecode.com/svn/trunk@4799 560a3889-bb33-0410-9f33-43a8a102dc09
* Do not use the "Databases" setting for the db tree, just use it to set the single db name in PostgreSQL mode.
* Use "postgres" as default db (was "template1")
* Turn checkable dropdown menu items into radio items in PostgreSQL mode
See issue #3190 and http://www.heidisql.com/forum.php?t=16072

git-svn-id: http://heidisql.googlecode.com/svn/trunk@4800 560a3889-bb33-0410-9f33-43a8a102dc09