hgweb: use generator to count parity of horizontal stripes for easier reading. - use web.stripes in all places and consistently - start with parity0 for lists generated in reverse (e.g. changelog)

0
0
adding changesets
killed!
transaction abort!
rollback completed
.hg/00changelog.i .hg/journal.dirstate .hg/requires .hg/store .hg/store/00changelog.i .hg/store/00changelog.i.a