Mutter bumped its API version to make all the new goodness parallel-installable with current stable ones, adjust to that.
Gah, this fell through the cracks ...
Update NEWS.
Meson is on track to replace autotools as the build system of choice, so support it in addition to autotools. If all goes well, we'll eventually be able to drop the latter ... https://bugzilla.gnome.org/show_bug.cgi?id=783229
