Add ScreenClicked()
Add Wavy_SCREEN() functionality.
Slowly adjusts the dimmers for sun and moon whilst drawing expanding
circles on the screen.  Tap screen to exit.
Change MAX_DIMNESS to 100 as the STM32 chip PWM has 100 steps.
Change Config_MLS_SCREEN to make better use of MAX_DIMNESS.
Adjust hardcoded defaults for sun and moon because of new MAX_DIMNESS.
Add file src/Bitmaps/button_skin100x30.bmp for use on skinned buttons.
Add #define for colour ORANGE.
Add support for transparent background on character drawing.
Add bitmap support to ButtonWidget.
Modify standard button dimensions to match those of skin bitmap.
Add DrawOutlineRect to gui.h/c
Add transparency support to DrawString.
Use lastbg in ButtonWidget to reduce button redraws and improve efficiency.
Update Release makefiles to reflect changes in Debug build.