Major changes:
* Configuration in ".mew.el", especially of mew-config-alist is
simplified. See the config2 node in info.
* Virtual mode is categorized to Selection and Thread. You can create
Selection by keyword, dialog, sorting, and so on. You can make
Thread even of Selection as well as of Summary.
* "S" is now virtual sort creating Selection. Physical sort is
assigned to "M-s".
* Punycode is supported. Mew now can display internationalized domain
names.
* "Z" collects a folder list according to the current world.
No numeric argument is necessary any more.
* "_" toggles a long line: normal, long, wrapped.
* You can use gmail with IMAP.
This changes the buildlink3.mk files to use an include guard for the
recursive include. The use of BUILDLINK_DEPTH, BUILDLINK_DEPENDS,
BUILDLINK_PACKAGES and BUILDLINK_ORDER is handled by a single new
variable BUILDLINK_TREE. Each buildlink3.mk file adds a pair of
enter/exit marker, which can be used to reconstruct the tree and
to determine first level includes. Avoiding := for large variables
(BUILDLINK_ORDER) speeds up parse time as += has linear complexity.
The include guard reduces system time by avoiding reading files over and
over again. For complex packages this reduces both %user and %sys time to
half of the former time.
