Log message:
Update PYTHON_VERSIONS_COMPATIBLE
- assume that Python 2.4 and 2.5 are compatible and allow checking for
fallout.
- remove PYTHON_VERSIONS_COMPATIBLE that are obsoleted by the 2.3+
default. Modify the others to deal with the removals.

Log message:
PYTHON_VERSIONS_ACCEPTED must be set before including pyversion.mk.

Log message:
Convert to use PLIST_VARS instead of manually passing "@comment "
through PLIST_SUBST to the plist module.

Log message:
Change the format of BUILDLINK_ORDER to contain depth information as well,
and add a new helper target and script, "show-buildlink3", that outputs
a listing of the buildlink3.mk files included as well as the depth at
which they are included.

For example, "make show-buildlink3" in fonts/Xft2 displays:

	zlib
	fontconfig
	    iconv
	    zlib
	    freetype2
	    expat
	freetype2
	Xrender
	    renderproto

Log message:
Track information in a new variable BUILDLINK_ORDER that informs us
of the order in which buildlink3.mk files are (recursively) included
by a package Makefile.

Log message:
Needs Python 2.3+

Log message:
py-numarray dependency support only Python 2.2 and newer.

Log message:
Uses C++.

Log message:
subprocess is only installed on Python <= 2.3. Conditionalize PLIST
accordingly. Bump revision.

Log message:
Bump BUILDLINK_ABI_DEPENDS.png and PKGREVISION for png-1.2.9nb2 update.