a start on std.regex conversion

few steps more
hacks on the way to integrate new uni into std.regex
workaround internal error
adjust Tries back to 2-level
another minor tweak, always use tries not sets for now
hack our way to make ctRegex work, some tests disabled
workaround stable sort (std.move) not CTFE-able
Kickstart not quite ready, casefolding too. Otherwise looks fine
introduce simpleCaseFolding to support case-insensitive regex
fix range violation for non-existant sets of length < 2
make simpleCaseFoldings CTFE-able
get our case-insensitive regex back
reanble kickstarter engine in std.regex
Get rid of internal.uni, internal.uni_tab

Saving amount to ~290Kb on 32bit.
fix 64bit bitrot