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)

#!/bin/sh

hg init
echo This is file a1 > a
hg add a
hg commit -m "commit #0" -d "1000000 0"
touch b
hg add b
rm b
hg commit -A -m"comment #1" -d "1000000 0"