Pending input refactor

Objective:

* Make all text inputs have the ability to be "pending", not just ones
  with a special mixin

Changes:

* Delete pending input widget
* Move pending input widget implementation to text input widget
* Update all uses of pending input widget
* Make pending image a reusable "texture"
* Update styles of text input widget for pending state
* Get rid of checking for mixin since all text inputs can be pending now

Bonus:

* Get rid of unused images, including .psd and .ai files
* Add transparency texture
* Fix input widget not using documented config value
* Fix documentation in select widget (lies!)

Change-Id: Ib46ab01dc39d706e5c25fd473dee0edce51b7e44
Merge "Pending input refactor"