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 files updated, 0 files merged, 1 files removed, 0 files unresolved
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)