Used by the routines at PARSE_ACTION and WOULD_WORK.

For a pattern with objects, the target and the instrument are each only names until something fits them. This goes through the objects that fit the target's name (NEXT_TARGET) and, for each, those that fit the instrument's (NEXT_INSTRUMENT), trying the action on each pair, and stops at the first that works. How many fitted is counted at TARGETS_FOUND to INSTRUMENTS_FAILED, and the first of each is kept at FIRST_TARGET_FAILED to FIRST_INSTRUMENT_FAILED, so that when only one thing fitted it is that one the refusal is about. The exact order of the fall-backs is not worked out in full.