New: column.index() API method for translating column indexes

- The fnVisibleToColumnIndex and fnColumnIndexToVisible plug-in API
  methods for the old API were very useful for transforming the visible
  column index to the actual index, and the return. This adds that
  capability to the new API.
New: rows().remove() API method

- Remove (delete) selected rows from the table.

- This effectively replaces the fnDeleteRow API method of the old API.
New: search() and columns().search() API methods

- Ability to filter the table through the new API.

- This effectively replaces the fnFilter method of the old API.

- Note that one capability which has been removed from the old API is the
  ability to not show the new filter on the filtering input elements. I
  can't see any use for that feature to be honest, so it has been
  dropped. The filtering inputs always show the global filter state now.

- Additionally, note that we've been forced to call this `search` here
  rather than `filter` since there is a `filter` method for the API
  collection instance. This might be revisted before release.
Internal: Update the the filtering input control to update itself on filter

- Previously it was the domain of the filtering caller to update the
  global filtering input element (fnFilter or the keypress handler
  specifically), but in keeping with the drive towards modularity, it
  should be the control itself that updates when needed.

- This is done by listening for the `filter` event from the table and
  updating the display as needed. It is a touch less efficent since the
  same value might be written as what is already there, but it reduces
  code size and complexity.