TTY Port, need to be tested...
STScreenBuffer : remove unused method
stringext.cpp : fix ascii2unicode & unicode2ascii

The conversion from ASCII to Unicode and vice versa are quite trivial. By design, the first 128 Unicode values are the same as ASCII (in fact, the first 256 are equal to ISO-8859-1).

So no need to use MultiByteToWideChar & WideCharToMultiByte API.
dlgFontEdit.cpp : fix build for linux target.
DrawText Format, add missing define
use XCSoar Brush as base class for LKBrush.
LKBitmap : remove copy ctor and copy operator.
use XCSoar Bitmap as base class for LKBitmap.
use XCSoar Pen as base class for LKPen.
add Features & Debug for XCSoar Screen class ...
LKFont : remove copy ctor and copy operator.
use XCSoar Font as base class for LKFont.