Make my-fold-dwim commands consistent.
Remove smart-tab customization, use native `tab-always-indent' instead.
Add my/ignore-buffer-p function for deciding what buffers are interesting.

Better separation of concerns here:
 - my-defaults.el only knows about built-in packages
 - other packages loaded later can add predicates to the ignore-buffers list
Make el-get available earlier.

I'm planning to refactor my-extensions.el further since the list of
packages is getting long. Might be useful to separate essential
packages I rely on from other stuff that is experimental or not always
needed.
Remove redundant el-get recipes.

These recipes are available with el-get now. Also remove smart-tab altogether.
Add ibuffer-vc package for grouping buffers by project as defined by version control system.
Move config related to extensions out of my-mode-line.el -- specifically for diminish.

Goal here is to be able to add/remove packages without having to make
changes in multiple places, e.g. without having to diminish new minor
modes in my-mode-line.el. New approach:
 - only deal with built-in modes in my-mode-line.el
 - add a function for diminishing new modes without having to care
   whether diminish itself has been loaded
Remove unnecessary eval-after-load from init-pabbrev.