First version of a vector-based "half-copying" merge sort, which will end up being more than twice faster than the current version.
First version of a vector-based "half-copying" merge sort, which will end up
being more than twice faster than the current version.

[Currently works only with 2^n lists, and otherwise broken -- committed
to keep the development history in svn.]

svn: r17001

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket