tests/test-diff-newlines.t

contrib: add a commit synthesizer for reproducing scaling problems

This adds two new commands:

- analyze examines an existing repo and writes out a statistical
  description of its properties that contains no identifying
  information.

- synthesize creates new commits based on the description generated
  by analyze.

The intention is that a repo constructed using synthesize will have
properties that are vaguely statistically similar to the originating
repo, but entirely random content.

This can be useful for forecasting performance as a repo grows, and
for developers who want to find bottlenecks in proprietary repos
to which they do not have access.

  $ hg init

  $ python -c 'file("a", "wb").write("confuse str.splitlines\nembedded\rnewline\n")'
  $ hg ci -Ama -d '1 0'
  adding a

  $ echo clean diff >> a
  $ hg ci -mb -d '2 0'

  $ hg diff -r0 -r1
  diff -r 107ba6f817b5 -r 310ce7989cdc a
  --- a/a	Thu Jan 01 00:00:01 1970 +0000
  +++ b/a	Thu Jan 01 00:00:02 1970 +0000
  @@ -1,2 +1,3 @@
   confuse str.splitlines
   embedded\rnewline (esc)
  +clean diff