Misuse of __WXWINDOWS__ for checking the presence of Windows. The correct
macro is __WINDOWS__ or __WXMSW__ in GUI programs.
__WXWINDOWS__ is always set, on all platforms.
Also adds indicators in layers palette for feedback.
Also generates sized images for all indicators instead of using
scaled bitmaps (which didn't look great).
Also fixes a completely unrelated typo in a UI string.
Init'ing static wxBitmaps in the global scope happens before the GUI is
ready, which segfaults, at least on GTK+. This can happen in, for
example, the Python module. In normal use, the singletop/kicad
loader has initialised the GUI first, so it doesn't manifest there.
The introduces INDICATOR_ICON, which is a very simple class holding a
bitmap that can toggle on or off.
The ICON_PROVIDER class then provides icons to INDICATOR_ICONS, which
means the class can be used for more than just row indicators.
A default row icon provider is also provided for use in the standard row
selector.
John Beard
Jeff Young
Chris Pavlina