`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
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.