t/issue282.t added: unshare_hek_or_pvn assertion
Makefile.PL: minor unicode warning change
CC 12 (eval) fails since 5.19.0
add t/testc.sh 282
C: aesthetics only
t/testc.sh: add 280
t/issue197.t: seperate -O3 issues, #208 vs #197. works fine 5.18-nt

5.18 threaded asserts at bless
t/testc.sh: fix broken tests 253 194
t/issue169.t: adjust testcount to 3
t/testc.sh: more format testcases #273, #283 (dupl of #238)
1.43_01: fix #277 non-static formatstrings with ~~

special case formline const strings. TODO: only with ~ in the string
t/issue282.t: add comment
C: non-static only ~ and ~~ formatstrings

slight optimization, rarely needed
#272: add testcases for uninitialized gp->hv slot

on gp->hv/sv mishmash
Fix issue #272, SvLEN=1 for empty heks

non-static, non-shared keys for such $hash{""} hash keys,
to avoid 5.10 wrong pv->hek offsets.
run-time still fails with such hek-asserts
C: revert reversing @dl_modules, enforce attributes first

but do not reverse the loading order otherwise
add 259 testcase
1.43_02: Fix empty shared heks finally

Use the static emptystring "\0" for such heks, and
patch destruct to SvLEN=0.
Now we can leave HvSHAREKEYS on for such hashes.
Fixes not all the #272 run-time and hek assert issues also.