New database setup config widget with more details about Mysql initial...

New database setup config widget with more details about Mysql initial configuration and more help to tune settings.
The MySQl Internal is now handle as a main database type config.
Screenshots :

https://www.flickr.com/photos/digikam/23121578776
https://www.flickr.com/photos/digikam/23147681465
https://www.flickr.com/photos/digikam/22851871180

BUGS: 233762
BUGS: 337443
BUGS: 262321
BUGS: 342124

FIXED-IN: 5.0.0