Proposal: --no-props switch for 'log', 'st' and 'diff'

In using merge tracking with 1.5.x and other branches, I've occasionally been
annoyed by the fact that mergeinfo mods can often overshadow the meat of a
change. I'd like to add a '--no-props' flag to 'log', 'st', and 'diff' which
would simply cause the subcommand to ignore property changes. It wouldn't be
the default, but it would clean up output and make using merge tracking a bit
easier.

I envision '--no-props' to be an all-or-nothing measure, initially, but we if
the demand was there, we could further expand it to '--without-prop FOO' which
would only omit changes to property FOO.

Thoughts?

-Hyrum