LinGui: add "Reload" and "Reload All" toolbar buttons to queue window
This allow reseting queue entries to the pending status so that they
make be re-encoded.

I'm not sure when a user might use these, but I have had many occasions where
I wish I had this capability during debugging and testing.


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6192 b64f7644-9d1e-0410-96f1-a4d463321fa5