cleanup std.regex CTFE hacks, it's working as is now
enable ctRegex tests, fix 3 latent bugs

Bad codegen for Backreferences,
wrong trackers used for nested infinite loops
and even wrong code for '.'
restore "multi-line" behaviour of '.' in ctRegex
catch the wrong test-case
fix faulty multi-line logic of Eol in ctRegex

Also reduce the amount of tests to run to let auto-tester breath freely
Add versioned blocks to partition test-suite in compilable parts
Merge pull request #1464 from blackwhale/ctr-enable-test

Enable ctRegex tests, fix 3 latent bugs
Introduce lookahead for ctRegex
safety of nested lookahead, enable all of R-T tests
Merge pull request #1465 from blackwhale/ctr-lookahead

Lookahead support for static regex aka ctRegex
Merge pull request #1459 from blackwhale/ctr-clean

cleanup std.regex CTFE hacks