unify error messages, save memory

[rurban]

unify error messages, save memory

[rurban]

Measured the impact: with the new errorhandling code and global errmsg table we need 30kb more,
and measuring the win with massif on the 4 so far changed unit tests measured so memory win at all.
given that the error messages degraded, it is rejected. I'll keep the branch errmsg-gh19 though

changed funcs for testing: vsnprintf_s, vsprintf_s, swprintf_s, vswprintf_s

massif test script: (darwin)

make all
test -f src/.libs/libsafec-3.0.3.dylib && strip -S src/.libs/libsafec-3.0.3.dylib
make -C tests t_vsprintf_s
strip -S tests/t_vsprintf_s
valgrind --tool=massif --massif-out-file=massif tests/t_vsprintf_s
grep -h mem_heap_B= massif | cut -c12-|sort -rn|head -n1

# 190515 errmsg
# 190515 sprintf