Issue #81: define window loyout independent of font and scale to fit display

- define an abstract class TDAbstractWindowProperties
  for import/export of properties
- TDStandardWindowProperties defines my standard
  layout with options for extra lists (on wide
  displays or small fonts) and control proportions
  of shell window and code window
- defined small/medium/large (0, 1, 2 extra lists)
  that match up pretty well with the layouts I've
  played with so far.