`mat2 -c file.pdf` should exit with an error message
The fact that the -c switch changed its meaning worries me a little.
People are used to write mat -c file.pdf
to check and show metadata
without writing anything to a file. Now, mat2 -c
is for checking
dependencies, and mat2 -c file.pdf
should fail with an error message.
Instead, it silently acts as if the -c switch was not there and
proceeds to clean the file.