Now prove_goalw_cterm calls print_sign_exn_unit, so that the rest
of the error message ("The exception above was raised for...") will appear.
And print_exn calls print_sign_exn_unit so that it can re-raise the SAME
exception.
#! /bin/sh
#rm-logfiles: remove useless files from subdirectories
rm log */make*.log */make*.log.gz
rm */test
find . -name '.*.thy.ML' -print -exec rm {} \;