Added pop-ups on links to picsarus.com
suppress pop-up on twitter login screen
Fix #108: TZP stops working on Nightly

Firefox 20 for some reason now calls image.onerror after calling image.onload,
which it never used to do.  That sequence caused a bad state.  Workaround implemented
is to disable image.onerror after image.onload gets called.  Seems to work
again.