revset: added lazyset implementation to matching revset
Performance Benchmarking:
$ time hg log -qr "first(matching(0))"
0:
9117c6561b0b
real 0m2.213s
user 0m2.149s
sys 0m0.055s
$ time ./hg log -qr "first(matching(0))"
0:
9117c6561b0b
real 0m0.177s
user 0m0.137s
sys 0m0.038s