complete mailto protocol handling, various fixed memory leaks, fixes for
crashes on multiple text selection, and a fix for misbehavior on failed
SMTP relaying.
improved address book handling, more reliable mailbox backend. The code
has however some experimental and unfinished features enabled so be warned!
The POP problems some people experienced have not been really addressed
yet.
Add a new USE_LIBTOOL definition that uses the libtool package instead of
pkglibtool which is now considered outdated.
USE_PKGLIBTOOL is available for backwards compatibility with old packages
but is deprecated for new packages.
