Add two buttons to move the currently selected field up or down to allow
changing the field order of a table.
Extend the DBBrowserDB::renameColumn() method to support changing the
position of a field.
Rename the files and classes for the dialogs to share all the same
naming pattern. This should make navigation in the code a bit easier.
Do not include dialogs not rewritten yet; they'll be edited as they are
redesigned.
