need an extra register in charrange
use charrange for all case sensitive ranges

Case insensitive charrange is implemented on moar only atm, and fails
the following spectests:
t/spec/S05-grammar/protoregex.rakudo.moar
t/spec/S05-mass/properties-block.t
t/spec/S05-mass/rx.rakudo.moar
t/spec/integration/advent2013-day18.t