[MERGE] Added support for a hook before sending the commit message to the editor.

[Monty Taylor]

Ian Clatworthy wrote:
> Monty Taylor wrote:
> 
>>> For command line hooks, stdin and stdout could be used for existing and
>>> new texts respectively.
>> Yes, ok. I've got a long plane flight tomorrow. I plan to work on this
>> (and a few other things)
> 
> Cool.
> 
> Just to be clear, I'm working on enhancements to the general hook code
> to support command line hooks - you don't need to do anything there,
> just support the Python hook signature as discussed.

Cool... I'm not sure I follow what you mean by command line hooks...