drawable: add a new progress dialog spinner

Fits much better than the standard one. Replacing the
spinner on all places where we use a progress dialog.

Also refactoring the trim-command a bit to use the new
thread-pattern.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>
helpers: call setChecked() on checkbox change

This fixes a nasty bug where the checkbox would return
to its previous state when onBindView() is called again.
This affects mostly CustomListPreference since it gets
drawn most probably, however this should be also added
to CustomTextPreference.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>