Values now displayed

Displaying the values in the second level menus now works.

The code to update the screen after a click has been move into one place to avoid duplicate code.
Added field-specific updates

Clicking something on the number pad will now update the value corresponding to the currently selected field.
Fixed number pad input

Number pad input now works for all fields.

Also fixed a bug where attempting to backspace with one digit remaining with an integer would give an error message and not change the integer.