Higher-level regexps as an ap_ utility

[Nick Kew <ni...@webthing.com>]

If noone objects, I propose to expand ap_regex/util_pcre a little
to support a higher level of regexp processing.

The basic motivations are:

1. A regexp object that includes memory (nmatch/pmatch), flags,
   and a substitution pattern, alongside the existing ap_regex.
2. One-stop compilation of Perl-style regexps such as s/foo/bar/i.
3. One-stop execution of a regexp on a string, including
   applying a replacement string where applicable.

Examples of where this would apply in existing code include
things like mod_substitute, mod_headers, and mod_rewrite.

What I've written so far is small and simple: a new type and
two functions (compile/exec).  That's all it takes!

Any objections?

-- 
Nick Kew