pidgin/nest

Change links pointing to trac to youtrack and other stuff on pidgin.im

Fix a bunch of urls to point to youtrack and other pages on pidgin.im

Testing Done:
None.

Reviewed at https://reviews.imfreedom.org/r/112/
Alan Hoskins <alanhoskins@gmail.com>
Elliott Sales de Andrade <quantum.analyst@gmail.com>
Frederick F. Kautz IV <fkautz@alumni.cmu.edu>
Gary Kramlich <grim@reaperworld.com>
Jason Allan <code@jasonderrythomas.com>
John Bailey <rekkanoryo@rekkanoryo.org>
Richard Laager <rlaager@wiktel.com>
Robert Vehse <robertvehse@fastmail.fm>
Zero <programmingzero@gmail.com>