Feature: column sort and resize

This adds sortable, resizable columns. Drag and drop columns to reorder, and drag from the edge of a column to resize. Your configuration is saved to `localStorage`. There is also a reset button in case you want your columns to go back to normal. :rocket:

Priorities for the near future:

- Redesign controls
- Add toggle-able columns

/cc @hueniverse @thegoleffect @wpreul