Pidgin 2.7.11

* General:
- Our bundled libgadu should now build on HP-UX.
- Fix some instances of file transfers never completing.
* Pidgin:
- Sort by Status no longer causes buddies to move around when you click them.
- Fix embedding in the system tray on older GTK+ releases (such as on CentOS 5.5 and older Fedora).
- No longer require libstartup-notification for startup notification support. GTK+ has included support for years, so use it instead.
* AIM:
- Fix a bug where some buddies from your buddy list might not show up. Affected non-English ICQ users the most.
- Send keepalives for all types of network connections. Will hopefully make chat rooms more reliable.
* MSN:
- Fix bug that prevented added buddies to your buddy list in certain circumstances.
* XMPP:
- Fix building on platforms with an older glib (inadvertantly broken in 2.7.10).
- Don't treat the on-join status storms as 'new arrivals'.
- Extend the /join command to support room JIDs, enabling you to join a room on any server.
- Add support for receiving a limited amount of history when joining a room (not currently supported by Pidgin and Finch).
* Yahoo!/Yahoo! JAPAN:
- Fix CVE-2011-1091, denials of service caused by NULL pointer dereferences due to improper handling of malformed YMSG packets. Thanks to Marius Wachtler for reporting this and reviewing the fix!