About one month worth of bsd.port.mk improvements.
(1) Allow multiple checksums of same file.
Submitted by: hoek
(2) Add "deinstall" target as an alias to "pkg_delete $(make package-name)"
(well, something like that, see diff for details).
(3) Add new port variable USE_AUTOCONF. It appends BUILD_DEPENDS to
devel/autoconf and runs autoconf before configure.
Submitted by: ohashi@mickey.ai.kyutech.ac.jp (Takeshi Ohashi)
(4) Clarify USE_X11 and USE_IMAKE usage.
(5) Add new user-overridable variable MASTER_SITE_KDE.
Submitted by: vanilla
(6) Add support for "Latest" package links.
Idea by: Terry Lambert
(7) Try to catch obsolete tcl/tk installations that could cause problems.
Annoyed by various bogus commits by: you-know-who