Some of the descriptions of command line options were getting quite
long, and when translated they are likely to grow even longer. This
word-wraps them at 70 characters, just like the help texts.
We could have opted to wrap them at the terminal width instead, but I
think it looks better to have them be consistent with the help texts.
We'd mistakenly made the -p option always on, which meant there was no
way to turn it off. It also meant that we were sometimes splitting
multibyte characters in function name, which isn't a good default.
- use "branch 'foo'" to distinguish from "branch merge".
- commit messags can be empty (to abort commits)
- Added value for editor message: Tell about HG: lines like CVS does.