Making progress on replacing segmented input.
Fixed merge conflict with new inputs.
Rewrite of the card number input field.
* Re-built arrow nav handler; fixes #38.
* Paste now works as expected; fixes #36.
* Key repeat works pretty nicely now; fixes #35.
* Select all now works as expected; fixes #29.
* Fixes issue with tab-focus change; closes #23.
* Unsupported chars are removed from pasted data; closes #22.