pngimage: add --list-combos
pngunknown: add --strict to catch warnings
pngvalid-standard: remove the spurious --progressive read (compare with
pngvalid-progressive-standard!)
This patch probably applies to 1.5 and 1.6 (where the tests exist) too.
Signed-off-by: John Bowler <jbowler@acm.org>
the massive speed improvements use a make capable of parallel builds
on a multi-CPU machine and pass the right arguments to make (-j10000
for GNU make) to get the build to run in parallel.
