Fixes for packaging

[purcell]

• Shorten package description line
• Fix formatting of trailing line
• Add autoload cookie

This is in connection with https://github.com/milkypostman/melpa/pull/1510.

I'd also suggest doing most of the work of the git-link function in a non-interactive function which could be called programmatically from elsewhere without messing up the kill ring -- this is potentially a widely useful utility function. :-)

[sshaw]

Thanks for the fixes.

Good point about the git-link and the kill ring. I'll make that change soon.