Merge branch 'ps/graph-lane-limit' into jch

The graph output from commands like "git log --graph" can now be
limited to a specified number of lanes, preventing overly wide output
in repositories with many branches.

* ps/graph-lane-limit:
  graph: add truncation mark to capped lanes
  graph: add --graph-lane-limit option
  graph: limit the graph width to a hard-coded max

diff --cc revision.c
Simple merge

diff --cc revision.h
Simple merge