* Update example sections to include basic, mobile-desktop, and mobile-tablet-desktop implementations
* Add more examples to the grid example page
* Red columns instead of gray for more Bootstrapy aesthetic

* Update docs to include table of grid levels and behaviors
* Change from .col-md to .col-sm to match existing size variables we use elsewhere
* Keep .col-lg as-is though for simplicity as we won't likely add a fourth level of the grid
* Combine responsive .container breakpoints with grid breakpoints in grid.less
* Other misc docs updates

I reworked the customizer to match the new docs layout and include all
newly added variables, etc.
Would be glad to keep an eye on Customize and update it as v3 changes.
Help blocks in my new version need some more work, too, so this is just
a basis.

* Update docs language
* Enforce display: block; on all utilities for now
* Fix up docs CSS for the tests

Sets `type="button"` on all buttons in the docs

* New padding approach with separate horizontal and vertical padding
variables
* Improved sizing in large and small buttons and form controls
* Dropped the `.btn-mini` (since we have no `.input-mini` to match, and
holy fuck those were small buttons)
* Dropped the `.pagination-mini` as well because once again, to hell
with such small components
* Changed `@line-height-headings` to `@headings-line-height`
* Removed the `@headings-font-family` because it was honestly kind of
useless

* Instead of 20px as @line-height-base, use 1.5
* Update typographic scale for headings to use unitless as well--required some twerking of decimals a bit and some rounding
* Introduce new @line-height-computed value, which takes base font-size and multiplies it by 1.5, for use in padding and margin on components

* Bring back the navbar up top
* Pull the docs content back into separate pages because a 6.6k line docs file is just crazy
* Recenter the page content and bring back affixed side nav (needs work)

* Switch from  to  to eliminate an element in selectors
* Drop .navbar-divider entirely