Add rewritten config, dubbed emacs-siren

I've taken a lot of inspiration from Emacs-Prelude when it came to the
structure of this rewritten config. I didn't want to use Prelude as I
don't agree with all it's defaults, nor do I want to have to deal with
any future changes in Prelude that might break things for me. So instead
I went down the fully custom path, but heavily inspired by Prelude, both
in terms of file/code structure, and also some of it's features.

Compared to my old config setup, it's got most of the same things, but
nearly everything is in a module file now, making it easy to fully
enable/disable certain features.

modules/siren-github.el

@@ -0,0 +1,10 @@
+;;
+;; github
+;;
+
+(siren-require-packages '(github-browse-file))
+
+(require 'github-browse-file)
+
+
+(provide 'siren-github)