color: add debugcolor command (issue4094) This patch adds a debugcolor command that prints all colors that the extension knows about.

revset: added lazyset implementation to merge revset Performance benchmarking: $ time hg log -qr "first(merge())" 102:58039eddbdda real 0m0.276s user 0m0.208s sys 0m0.047s $ time ./hg log -qr "first(merge())" 102:58039eddbdda real 0m0.192s user 0m0.154s sys 0m0.027s