MutltiArray is CTFE-able; corrections for workarounds in std.uni
refactor TrieBuilder
tweak algorithm to actually fast-track zero-pages

Also significantly speed up replicateBits for single bit pattern case.
other tweaks for std.regex/ctRegex
fix 64-bit issues
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