Adding catch().err / .value, regexp and regsub

[ldemailly]

regsub has 2 variants, default 2 args is just boolean match, 3rd arg true it returns all the first matches

Fixes #105

it's a tiny bit costly

┌─────────────────────────────────────────────────────────────────────┐
│ Diff between grol_noregexp and grol                                 │
├──────────┬──────────────────────────┬──────────┬──────────┬─────────┤
│ PERCENT  │ NAME                     │ OLD SIZE │ NEW SIZE │ DIFF    │
├──────────┼──────────────────────────┼──────────┼──────────┼─────────┤
│ +100%    │ regexp                   │          │ 131 kB   │ +131 kB │
│ +121.01% │ unicode                  │ 14 kB    │ 30 kB    │ +17 kB  │
...
│ +4.69%   │ grol_noregexp            │ 6.8 MB   │ 7.1 MB   │ +318 kB │