defined_cv: Skip saving defined(&cv) subs (#96)

Enable t/issue96.t
Add helper functions from oldmaster: svop_name, padop_name
use global curcv for pads
add GV::save filters, e.g. 8: do not save CV
added nextcop arg to method_named to get proper location info on -DC
t/testc.sh: add 2900 for issue 29 (B::C open utf8)
1.43_05: fix format STDOUT/STDERR

added all format testcases to t/issue238.t
t/fast-testing.sh [--coproc] cproc optional

coproc only works with bash-4, and it kills all processes with matching names
even in other ttys
prepare empty-cv tests: MANIFEST, t/issue251.t
1.43_06: Save empty bodyless cvs if they exist even if not defined

seperate defined &$sub from exist &$sub (thanks Dan Muey)
needed for signal handlers, prototypes declarations and cvrefs
(#251, #159, #235, #246, #270, #271, #275, #279)

$SIG{__WARN__} = sub{} behaves correctly now again.
Changes, STATUS: update
1.43_07:  Fix PVMG PV overwriting the RV, overload sub (#273)

A PVMG RV (ref) to a an attached overload sub was overwritten by an
empty PV. This also caused a "Attempt to free unreferenced scalar: SV"
Added t/issue273.t
#273: fix various regressions

#159, 259, ...
set $static on an ROK slot in any save_pv_or_rv, so that the RV is not
overwritten by the PV
update module tests for 1.43_07 3ce6b09, no changes
t/issue172.t added. with and without manual workaround -uFoo
C 1.42_67: mark empty overloaded package

This is merely workaround for reduced testcases, such as the core testsuite
or issue 172. In practice all overloaded packages had some functions defined.
test update todos: 31, 169
test update todos: 242 (To/Title dynaload). fails threaded and <5.14
C: save utf8::SWASHNEW even <5.14 on unicore/To/Title.pl or utf8_heavy.pl

fixes most issue242.t tests, just threads remaining
C: fix #242 >5.14

check for unicore/To/Tc.pl and unicore/Heavy.pl also and
mark utf8 and utf8_heavy.pl do they dont get deleted.
5.14.4 threaded still fails for different problems
untodo test 143
module tests updated: all good
C: fix #267 no SvSTASH on 5.18 overloaded %version:: stash

we store now also magic from stashes for PMOP #188, but we need to skip
SVf_AMAGIC (overloaded) stashes, since they crash with GetOpt::Long at SvSTASH.
%version:: and %Errno:: only.
module test updates for 1.42_67 0cbc49a

Getopt::Long passes now, untodo more passing tests