generalize the folding from Core.thy to later theories, so that for instance all_meta_trs can be called in all_meta_tr whenever it would be needed for a command to recursively generate several meta-commands


git-svn-id: https://projects.brucker.ch/hol-testgen/svn/HOL-TestGen/trunk/hol-testgen@13499 3260e6d1-4efc-4170-b0a7-36055960796d