2 concrete classes which are currently implemented:
* BSpinner (works on int32s)
* BDecimalSpinner (works on doubles)
In addition BAbstractSpinner now inherits from BControl instead of
BView/BInvoker. This allowed for code simplification at the cost of needing to
cast for the decimal version because SetValue(int32 value) comes from BControl.
Also, add a spinner_button_style enum with 3 options:
* SPINNER_BUTTON_HORIZONTAL_ARROWS
* SPINNER_BUTTON_VERTICAL_ARROWS
* SPINNER_BUTTON_PLUS_MINUS
which sets the spinner arrows to either use horizontal arrows (left/right)
vertical arrows, (up/down), or +/- symbols (the default).
If the spinner button is using horizontal arrows you can decrement and increment
the spinner value by pushing control+left/right, otherwise you can increment and
decrement by pushing up or down. The reason for needing control is so that you
can move the cursor in the textbox otherwise.
Switch the 3 apps that are currently using BSpinners to use the integer variety
in Deskbar preferences, WebPostive preferences, and Screen preferences.
