Change several instances of "git cl" in the Contributors Guide to "git-cl".

Change several instances of "git cl" in the Contributors Guide to "git-cl".

[john3, 2016-01-06 16:17:26]

Correct a misspelling of "always".

[benko.pal, 2016-01-09 13:59:16]

Is this needed in some environments/with some git versions?  git cl with a space
always worked for me (just as all the regular git commands did).
It doesn't hurt though, so LGTM.

[john3, 2016-01-09 14:45:50]

Benko,

I made the changes to create more consistency in the documentation. The
Contributor’s Guide sometimes said “git cl” and sometimes said “git-cl”. Being
new to LilyPond development and needing to learn how git-cl works, I found it
confusing that there were two different ways of talking about the same thing.
Several times I searched the Contributor’s Guide for instances of “git-cl” and
did not understand why I didn't find what I was looking for. 

John

> On Jan 9, 2016, at 8:59 AM, benko.pal@gmail.com wrote:
> 
> Is this needed in some environments/with some git versions?  git cl with
> a space always worked for me (just as all the regular git commands did).
> It doesn't hurt though, so LGTM.
> 
> https://codereview.appspot.com/282960043/

[paul_paulwmorris.com, 2016-01-11 19:08:43]

> On Jan 9, 2016, at 9:45 AM, John Gourlay <john@weathervanefarm.net> wrote:
> 
> I made the changes to create more consistency in the documentation. The
Contributor’s Guide sometimes said “git cl” and sometimes said “git-cl”. Being
new to LilyPond development and needing to learn how git-cl works, I found it
confusing that there were two different ways of talking about the same thing.

I had this same confusion.  It will be good to have more consistency on this. 
Thanks, -Paul