Refactored code relating to image buttons
Added ability to set brush width. Shows a dynamic brush stroke with current color preview
Fixed rounding of line in width preview. Added more documentation
Added eraser and brush/eraser width display. Long click on brush button changes from brush mode to eraser mode & vice-versa.
Background of bitmap is now white. Eraser erases to white. The previous color selected before the eraser is loaded back when changed to brush mode. Added save button but is not working completely.