Update to 2.15.2

* Remove or modify some patches that is obsolete or fixed in another way
  like devel/xulrunner.

Changelog:
Fixes in 2.15.2
    Applications could not be removed from the "Application details" dialog under Preferences, Helper Applications (bug 826771).
    View / Message Body As could show menu items out of context (bug 831348).

Fixes in 2.15.1
    Problems involving HTTP proxy transactions have been fixed (bug list).
    The Unity player crashed on Mac OS X (bug 828954).
Updated www/seamonkey to 2.15.2