issue 719: fixed numeric pattern

[Eloar]

fix for #719, simple escape for invalid character.

[rudiedirkx]

Good point. To be sure, add another \ to escape the \ itself. PHP doesn't need that, but it is more readable.

[Eloar]

\ escaped. I don't necessarily see it as an improvement in readability, but won't argue against that change.

[rudiedirkx]

In json it's a mandatory escape, in regex too (if you want to match a literal \), only in PHP it's not. I like to keep them similar. Anyway, good catch, thanks 👍