tests/test-diff-newlines.t

subrepos: abort commit by default if a subrepo is dirty (BC)

This changeset flips the default value of ui.commitsubrepos setting
from True to False and adds a --subrepos flag to commit.

The commit, status, and diff commands behave like this with regard to
recusion and the ui.commitsubrepos setting:

          | recurses      | recurses
          | by default    | with --subrepos
  --------+---------------+----------------
  commit: | commitsubrepo | True
  status: | False         | True
  diff:   | False         | True

By changing the default from True to False, the table becomes
consistent in the two columns:

* without --subrepos on the command line, commit will abort if a
  subrepo is dirty and status/diff wont show changes inside subrepos.

* with --subrepos, all three commands will recurse.

A --subrepos flag on the command line overrides the config settin.g

  $ hg init

  $ python -c 'print "confuse str.splitlines\nembedded\rnewline"' > a
  $ 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