[1.8.0 RFD] Homogeneous use of short options

Proposal: Make our use of short options more homogeneous.

I have put together a list of options which are used by the "most common commands", using the output of "git --help-all":

http://repo.or.cz/w/git/mjg.git/blob/options.txt

(scroll down for the short options)

This leaves out a few commands with different option parsing (diff, log, rebase, show) but indicates that we're doing a good job already. A few notable outliers:

add -A: Why capital A? Compare commit -a etc.

commit -n, fetch -n, merge -n: These are REALLY bad! Users should be able to rely on '-n' being '--dry-run' or at least being no-op to their repo, like clone/grep/tag -n.

tag -v: This is not a real problem, but users have certain expections for "-f,-h,-n,-v" which we should break as rarely as possible. OTOH, what would "verbose" mean for tag? (NB: tag.txt is grossly wrong.)

grep -?: This tries to be compatible with GNU grep, so it's a natural outlier.

Risks: Users and scripts may obviously depend on the current options names.

Migration plan: Introduce new options first (1.7.x) along with warnings in the release notes (optionally, make the commands output warnings). Then change the behavior in 1.8.0.

TODO: Generate an option list for the other common commands.

I'll also follow up with a little series fixing inconsistencies in the descriptions.