revamped FileFilterExt

the "Open File" dialog was too annoying for me.
I pimped FileFilterExt to be more convenient and especially do no longer force the user to select the filetype in the dialog
BEFORE picking a file.

Change-Id: I60a5a495aa67ec26259a5b8abec8e3b89c1c04eb
cleanup

Change-Id: I6bef1020c1f8cee7057a59c688268faeb1c62bdb
cleanup

Change-Id: Ia93b8ccc27eb64709f8fa75eb3b7fa126017811a