BMViewDlg improvements, Go button
Sort associated programs in Open With menu
AppList Rename implemented
Bug fix: couldn't add new progs

Bug was: You couldn't add new progs because
FileViewManager::AddOrEditSystemApp only expected a SAID of -1 for new
apps, while we passed -2 and this inserted wrong values in the DB.
Sort OpenWithDlg AppList
OpenWithDlg AppList Show associated progs bold
OpenWithDlg AppList: Sort and show assoc apps separately
Introduce FileViewManager::UnAssociateApplicationWithExtension
Implement un-association UI ('Dont show in Menu')
Enable SQLite Foreign key support in DatabaseManager, Bugfix

This causes more integrity in the database. I did it because it
simplified removing System Apps together with their preferred/associated
things altogether.
Also fixed unreachable code in DatabaseManager::BackupOpenOrCreate.
Prior to this, all databases where invalid which caused them to use
application's default database.
Implement FileViewManager app check and delete functions