Extended splitting for "git add --interactive"

Hi!

This is for git-1.7.12 (an older version from the SLES11 SP3 SDK). If the issue is solved meanwhile, I'll be happy, and I apologize for being too lazy to find out.

Currently Git cannot split a block of changes like

-AAA
-BBB
+CCC
+DDD

Into
-AAA
+CCC
and
-BBB
+DDD

So you'll have to edit it and waste me extra time (People probably use split if they know what they are doing, so maybe allow that).

Another split that is not possible is a split across an empty line, like:

+AAA
+     <empty line (in reality)>
+BBB

One could split that either into two parts with the empty lines belonging to one of AAA or BBB, or into three parts where the empty line is just another junk to accept or refuse. See comment above on why I'd like that.

Regards,
Ulrich Windl