added supporting functions for BootPage
removed init() from classes, it was stupid to begin with
handleButtonInput() and handleKnobInput no longer optional
added callback member to SelfTestField
placement position value fixes
use gfx.Translate instead of explicitly setting off-origin x,y values
added MARGIN and PADDING calculations to fields
removed unnecessary gfx.BeginPath() calls
Hersi
f44ba3743b