Correct org-blank-before-new-entry setting

377abd6 sets this with one value, but it needs to be an alist and have a
values for both heading and plain-list-item.
Do not expand change when commit with magit

Reverts c72bc96.
Remove useless defcustoms
Follow Purcell's emacs.d structure

User init files are added using provide/require.

https://github.com/purcell/emacs.d
Reorganize and use require-package

`require-package' is from
https://github.com/purcell/emacs.d/blob/master/lisp/init-elpa.el.
Only require untracked if it file exists
Remove unneeded url-handlers import
Remove unneeded loads in init-tex