gitweb: Bulk load commit objects

The following is a set of patchs which should improve the preformance of gitweb by bulk loading commit objects.

Note's:
* With a slight change in command line options and the parsing logic it was possible to bulk load the history action aswell.

* Even without the rev-list --skip option there should be some improvement as it is possible to bulk load the first page of commit object.

[PATCH 1/8] gitweb: Add parse_commits, used to bulk load commit objects. [PATCH 2/8] gitweb: We do longer need the --parents flag in rev-list.

Base support for bulk loading commit objects.

[PATCH 3/8] gitweb: Change summary, shortlog actions to use parse_commits. [PATCH 4/8] gitweb: Change log action to use parse_commits. [PATCH 5/8] gitweb: Change header search action to use parse_commits. [PATCH 6/8] gitweb: Change atom, rss actions to use parse_commits. [PATCH 7/8] gitweb: Change history action to use parse_commits.

Convert all the commit listing actions (except pickaxe search) to use parse_commits, also fixes up a few nav links.

[PATCH 8/8] gitweb: Use rev-list --skip option.

This change requires the rev-list --skip change from next to have been merged.

Robert