* More informative rewrite test output
When running rewrite tests, the output in case of a test failure now
includes not only the rewritten URLs but also the from URL.
* Move re-escaping to regexpMatches
This commit moves the code to post-process the match replacements from
ComplexRule to regexpMatches, so it can later be re-used for SimpleRule.
Also changes the comment in an attempt to better explain the reasoning
behind that code.
The required strings.Replacer is now built only once.
* Support regex captures in simple rewrite rules
Closes#2586
4bad5c79be