Scanning Improvements

[joereddington]

Scanning looks great so far, there are a couple of things to add and some very minor adjustments:

• Move the scanning switch into the settings page (it's a long term setting)
• in settings add a control to adjust the amount of time that the cursor stays on a box
• currently we have linear scanning, but we want to have also have row/column scanning as well.
• allow the user to switch between scanning modes in settings.