[configure] 'cover_new' target replaces 'cover'
[configure] 'cover_new' target replaces 'cover'

cover_new uses the tools/dev/make_cover.pl script to process the files
created from a coverage test run.  This is much more flexible and easier to
maintain than trying to get 'make' to do the right thing.

Also, the 'cover' target was running only the runcore tests and not the
standard test suite (a.k.a 'make test'), hence the output from 'make cover'
wasn't telling us what was being covered in 'make test', leading to
unexpected and confusing results (e.g. that extend_vtable wasn't being
tested at all).  The principle of least surprise suggests that 'make cover'
should run the same tests that 'make test' runs.

parrot/parrot,youprofit/parrot,tkob/parrot,FROGGS/parrot,parrot/parrot,youprofit/parrot,youprofit/parrot,FROGGS/parrot,FROGGS/parrot,FROGGS/parrot,youprofit/parrot,parrot/parrot,tkob/parrot,parrot/parrot,tkob/parrot,FROGGS/parrot,youprofit/parrot,tkob/parrot,youprofit/parrot,tkob/parrot,parrot/parrot,tkob/parrot,tkob/parrot,youprofit/parrot,tkob/parrot,youprofit/parrot,FROGGS/parrot,FROGGS/parrot,FROGGS/parrot