patch: enable diff.tab markup for the color extension The following patch splits up changed lines along tabs (using re.findall), and gives them a "diff.tab" label. This can be used by the color extension for colorising tabs, like it does right now with trailing whitespace. I also provide corresponding tests.

dirstate: copyedit exception for no beginparentchange call

revsetbenchmarks: add an additional roots() benchmark The existing roots(x - y) revset only considered the most recent 100 revisions. This was a good start. But expanding it to the full history of the repository can dramatically increase execution time and thus constitutes a useful benchmark.