New: Rewrite of how pagination is handled to make it hugely more
flexible and simple to actually use.

New: Two additional built-in pagination types: 'simple_numbers' and
'full'.

Update: 'two_buttons' type pagination (previous default) renamed to
'simple'.

New: Default pagination type is now 'simple_numbers'.

New: Introducing renderers to DataTables (something that will play an
important part moving forward).

New: Simplified pagination button classes to simply:
 * "sPageButton": "paginate_button"
 * "sPageButtonActive": "current"
 * "sPageButtonDisabled": "disabled"

- The basis for this commit is a restructuring of how pagination
  plug-ins work in DataTables, whereby the pagination plug-in simply
  returns an array of button types which should be shown. These are then
  actually displayed by the renderer. This seperates the logic for which
  buttons to show from the display logic, making it much easier, both to
  customise which buttons will be shown, and for integration plug-ins to
  customise the display of the buttons (since they don't need to
  replicate the button calculation logic). This change allows us to
  introduce two new built-in pagination types to DataTables with minimal
  size cost. Indeed, this change as a whole reduces the compressed
  DataTables size by 2.5K (additional functionality, simpler and smaller
  - what's not to like!?).

- Pagination button classes in DataTables were a mess before, with
  different classes used for the two built in types, with the additional
  complexity of only one of the defined class options being used, rather
  than concatinating the classes based on the type. This was bonkers and
  a barrier to new users styling the form as they wanted. Reducing to
  just three class options, and having the active and disabled options
  added to the base class makes it MUCH simpiler. This could hit
  backwards compatiblity for those who had styled the mad old style, but
  it would have been crazy to keep it while writing the rest.