Add makefile and version file that can be used alongside build script

[nbeaver]

The build script works fine, but I'm more familiar with makefiles. No hard feelings if you'd rather not use make.

[mikehardy]

Hmm - this one I don't like.

• Javascript development is mostly based on the node ecosystem now which is going to use package.json, and does things in package.json script entries called by npm run foo or yarn foo
• we already have a shell script that makes the XPI this duplicates it

What I'd like to see is more of an expansion of the javascript work - a lint entry in scripts for instance, and a build entry in there that called the makeXpi.sh script that exists so the construction is defined in only one place

[nbeaver]

Fine by me.

[mikehardy]

Thanks for understanding. The old school coder in my likes how fast make is but it's 2020, we can't do anything now without it actually being completed by javascript (somehow!?!) and virtualized a minimum of 3 more times before hitting the metal. What a time to be alive.