maketx unit test, oiiotool --metamatch --no-meta-match, IBA::fixNonFinite fix

1. Add --metamatch and --nometamatch arguments to oiiotool. When used in conjunction with --info -v (prints all metadata of the files it reads), it allows you to give regular expressions that specify metadata names to print (only) or suppress, respectively, 

The reason this is helpful is for testuite -- some things we may want to test (maketx, to pick an example) tends to time-stamp or version-stamp some fields. This will cause spurious test failures because of the things that vary from run-to-run or release-to-release, for testsuite tests that happen to want to dump all the metadata of a file that's created on the fly.

2. At long last, add testsuite/maketx, which is (almost) a comprehensive test of every maketx option.  It tends to work by making a bunch of textures and dumping their info to be sure they're built properly for the particular args being tested.  You can see now why number 1 above is important.

3. Along the way, I discovered some bugs in ImageBufAlgo::fixNonFinite. that caused it to not work properly for 'half' buffers.