Fixes #495 - Adds input clear button

- Adds search input manager for handling input clear button—little (x).
- Disables autocomplete because field highlight color can’t be
overridden.
- Removes unused data-list attributes.
- Adds tests for clearing the input fields.
Refactors class names

- Normalized button and form id/class names using the specificity
principle.
- Removes unused classes from submit/reset buttons.
Turn autocomplete back on.

I think autocomplete is too useful a feature to turn off just for
cosmetic reasons.
Merge master and fix conflicts.
Merge branch '495-clear-button'