feature request: better support for typos

Hi,

when a user made a typo, Git is not good in guessing what
the user could have meant, except for git commands. I think
this is an area with room for improvements.
Let's look into branches. When I "clone --branch" and make
a typo, Git could show me what branch I could have meant. It's
the same when I try to merge or track a branch. It might even
be possible to show suggestions for options for all Git commands.
What I'm trying to say is, there are arguments with a limited
amount of possible values that Git know, so Git can show
suggestions when the user made a typo for such an argument.

Ralf