Allow test output to exclude certain metadata when printing image info.

This uses the --no-metamatch option recently added to oiiotool.
This is really handy for certain tests that involve dumping oiiotool --info,
to simply make it not print the fields that might change from run to run
(like DateTime), or release to realase (like Software) and thus make
spurious testsuite failures.
Fix minor bugs that let IBA::fixNonFinite work properly with 'half' images.
Add testsuite for maketx