record extension default prompt choice

[Giorgos Keramidas]

I often find myself hitting 'n' in large sets of changes just to pick
one out of many.  It appears that for cherry-picking a small part of all
the workspace changes it would be useful to me to be able to run the
record extension in a mode where:

  - the default prompt choice for files is still 'yes', so I get to see
    the diffs for all modified workspace files
  - the default prompt choice for diff hunks is 'no', so I only have to
    keep hitting RETURN until I see the few changes I want to record

How would you call this sort of option in the command line of record.py?

I was thinking of something like:

  hg record --only-selected