Updated settings menu user interface to provide a friendlier user experience.

* NEW! Added flash card mode to aid in your ABG learning
* NEW! Added ability to switch the left and right displays (in settings menu)
* NEW! Added visual and auditory cues to alert player that challenge mode is ending.
* NEW! Added visual cue to alert player of incorrect game piece placement.
* FIX - Bonuses in challenge mode now appear more frequently.
* Addressed any additional program stability and optimizations.

* Added a new challenge mode designed to test your ABG knowledge
* Bug fixes and general app optimizations

Buttons are easier to press.
Changed uncompensated icon label from "NONE" to "UNCOMP"

You now have ability to choose whether to drag values to columns or simply tap the value and then tap its corresponding column.

Fixed UI issues with text not rendering properly across different screen resolutions.
Improved touch responsiveness to certain buttons in UI.
Added app previews.

Users can now drag and drop ABG values onto Tic-Tac-Toe board.
Adjusted UI settings for a better user experience.
Fixed issue with UI inconsistencies amongst different devices.
Minor bug fixes