Major update to the revision traversal logic to improve culling of
irrelevant parents while traversing a mergy history.
* kb/full-history-compute-treesame-carefully-2:
revision.c: make default history consider bottom commits
revision.c: don't show all merges for --parents
revision.c: discount side branches when computing TREESAME
revision.c: add BOTTOM flag for commits
simplify-merges: drop merge from irrelevant side branch
simplify-merges: never remove all TREESAME parents
t6012: update test for tweaked full-history traversal
revision.c: Make --full-history consider more merges
Documentation: avoid "uninteresting"
rev-list-options.txt: correct TREESAME for P
t6111: add parents to tests
t6111: allow checking the parents as well
t6111: new TREESAME test set
t6019: test file dropped in -s ours merge
decorate.c: compact table when growing