Log Message:
Update libpurple and friends to 2.5.8.  Changes:

ICQ:
* Fix misparsing a web message as an SMS message. (Yuriy Kaminskiy)

MSN:
Increase NS command history size to prevent crashes on buddy lists that
  have a lot of buddies on other networks like Yahoo!.

MySpace:
* Accounts with empty buddy lists are now properly marked as connected.
* Fix receiving messages from users of MySpace IM's web client.

Yahoo:
* Fixed phantom online buddies.  They should now properly disappear when
  signing out.
* Fixed the crashes some users were seeing with cn.scs.msg.yahoo.com in
  2.5.7.
* Fixed compiling on systems with glib 2.4.x or older.
* Fixed an issue with file transfers.  This may not resolve all issues,
  but it should resolve at least some of the most common ones.
* The pager server will automatically update to scsa.msg.yahoo.com if the
  user empties the field or if it is scs.msg.yahoo.com.  This should ease
  the pain of transition to the new login method.

XMPP:
* Fix an incompatibility betweeen Prosody and libpurple clients.