(Re) Wrote a tool to test NIF files in BSAs and on the filesystem.

Just give it a set of files, one file per argument, and it will make sure openmw can read them.

On linux/mac you can use "xargs --arg-file=nifs.txt ./niftest" to give it a list of files to check.
Disable building nif file tester by default
Merge remote-tracking branch 'emperorarthur/niftest'