debugindex: add --format flag to allow debugging parentdelta -f 1 shows extra data from revlogv1 (aka revlogng) including flags and size (based on a patch by Pradeepkumar Gayam <in3xes@gmail.com>)

pager: make example of setting pager less silly

convert: Work around p4 instability (issue2465) The p4 command-line client sometimes fails upon doing "p4 describe" when trying to produce a patch. (I'm guessing it's a bug in p4.) However, "hg convert" doesn't even make use of the patch, and it can be elided by adding "-s" to the p4 command line here.

revlog: choose best delta for parentdelta (issue2466) When parentdelta is enabled, we choose the delta that has the minimum distance to its base. Otherwise, base may be sufficiently far away to require a full version, resulting in greatly reduced compression.

revlog: precalculate p1 and p2 revisions

revlog: extract delta building to a subfunction

revlog: simplify cachedelta handling

revlog: fix buildtext local scope buildtext stores its result in _addrevision scope to avoid repeated builds cachedelta is already visible

merge with i18n

i18n-ja: synchronized with 6f6f6a9c2a41