Installer updates to use DBAPI 

Database calls chanelled through DBAPIclass;
Typo fixed in action.connection.php (changeable/changable)
Default for @installset made array() instead of false in setup.info.php (avoid spurious warnings during installation)

mysql DBAPI class updates for use with installer 
Allow for connection without database name
Remove check for mysql_real_escape_string and deprecated mysql_escape_string()
add option for text mysql error
add no-exit test for database connection & selection