[perl #123814] grok_atou() for regexp quantifiers

I've repushed branch hv/grok with a second commit as a proof of concept. There's a few loose ends, but should be enough to see how much you like or hate it - passes a basic test run except for XS-APItest, for which I'll need to acquire some XS fu.

Hugo

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via perlbug:  queue: perl5 status: open
https://rt.perl.org/Ticket/Display.html?id=123814

• Re: [perl #123814] grok_atou() for regexp quantifiers by wolfsage
• Re: [perl #123814] grok_atou() for regexp quantifiers by hv
• Re: [perl #123814] grok_atou() for regexp quantifiers by wolfsage
• Re: [perl #123814] grok_atou() for regexp quantifiers by wolfsage
• [perl #123814] grok_atou() for regexp quantifiers by Hugo van der Sanden via RT
• Re: [perl #123814] grok_atou() for regexp quantifiers by wolfsage
• [perl #123814] grok_atou() for regexp quantifiers by Hugo van der Sanden
• Re: [perl #123814] grok_atou() for regexp quantifiers by demerphq
• Re: [perl #123814] grok_atou() for regexp quantifiers by Jarkko Hietaniemi
• Re: [perl #123814] grok_atou() for regexp quantifiers by Jarkko Hietaniemi
• Re: [perl #123814] grok_atou() for regexp quantifiers by Jarkko Hietaniemi
• [perl #123814] grok_atou() for regexp quantifiers by Hugo van der Sanden via RT
• Re: [perl #123814] grok_atou() for regexp quantifiers by Jarkko Hietaniemi
• Re: [perl #123814] grok_atou() for regexp quantifiers by Jarkko Hietaniemi
• [perl #123814] grok_atou() for regexp quantifiers by Hugo van der Sanden via RT
• Re: [perl #123814] grok_atou() for regexp quantifiers by Craig A. Berry
• [perl #123814] grok_atou() for regexp quantifiers by Hugo van der Sanden via RT
• [perl #123814] grok_atou() for regexp quantifiers by Hugo van der Sanden via RT
• [perl #123814] grok_atou() for regexp quantifiers by Hugo van der Sanden via RT
• [perl #123814] grok_atou() for regexp quantifiers by Jarkko Hietaniemi via RT
• Re: [perl #123814] grok_atou() for regexp quantifiers by demerphq
• Re: [perl #123814] grok_atou() for regexp quantifiers by Jarkko Hietaniemi
• [perl #123814] grok_atou() for regexp quantifiers by Hugo van der Sanden via RT
• [perl #123814] grok_atou() for regexp quantifiers by Karl Williamson via RT
• Re: [perl #123814] grok_atou() for regexp quantifiers by demerphq
• Re: [perl #123814] grok_atou() for regexp quantifiers by Karl Williamson
• Re: [perl #123814] grok_atou() for regexp quantifiers by demerphq
• [perl #123814] grok_atou() for regexp quantifiers by Jarkko Hietaniemi via RT
• [perl #123814] grok_atou() for regexp quantifiers by Jarkko Hietaniemi via RT
• [perl #123814] grok_atou() for regexp quantifiers by Hugo van der Sanden via RT