Setting no limit size to trash directory is now possible using zero as value.

Setting no limit size to trash directory is now possible using zero as value.
A tooltip was added to the spinner to inform the user of this possibility.
When 0 is set, no remaining/free space check occurs.
Default size of the trash was set to a 128M and maximum size is now 2048MB, which
is more conform to today's standards.
The delete dialog now displays more information:
- if external command will be used
- if safe delete is on, max size and path to the trash
- if safe delete is off