fpg_panel: Refactored the HandlePaint method.
fpg_panel: Refactored the HandlePaint method.

* It was extremely hard to maintain that method as all Shape types
  drawing code are mixed together.
* Not all shape types (eg line top,bottom,right,left) was painted
  100% because of shared code.
* Each shape type now has its own DrawXXX method, with the result
  both issues mentioned above are resolved.

wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI