LKObjects: convert stock LKBrush copies to macros
Progress: take LKBrush reference instead of copying it
Screen/LKSurface: add SelectObject(HFONT/HBRUSH/HPEN) overloads

Replaces all old SelectObject() overloads.  The new ones are inlined
and have thus zero overhead over raw GDI function calls.
Screen/{Pen,Brush}Reference: new class replacing LK{Pen,Brush} in some cases

Used to avoid instances with _Destroy=false, only referring to the
"real" object.

As a side effect, this patch removes a lot of bloat (binary size
reduced by 10 kB).
Screen/LK{Brush,Pen}: disallow copies

Prepare for eliminating the _Destroy flag.
Screen/LK{Brush,Pen}: eliminate the _Destroy flag

All instances are now "master", and there are no references.
Screen/LK{Brush,Pen}: inline the default constructor

Reduce bloat.
Merge pull request #11 from MaxKellermann/linux

Brush/Pen optimizations, nearly ready for adopting XCSoar's portable Brush/Pen classes