Core: Kill off Host_UpdateBreakPointView()

Uses wxWidgets event propagation to the parent window which then appropriately handles the breakpoint list updating.
UnitTests: Get rid of now-nonexistent Host_GetInstance() within StubHost
Core: Kill off Host_UpdateLogDisplay()

This was actually never used as far as I can tell. There was no wx event handling done whatsoever for the global ID, So this is basically a dead function.
D3D: Remove an unnecessary call to Host_GetRenderWindowSize()
WGL: Get rid of the use of the Host_GetRenderWindowSize() call.

Just use the Windows API to accomplish the same thing (this is what is done in Update()).

This makes the backing window handle the correct data-type for Windows for easier use in function calls.
AGL: Remove the call to Host_GetRenderWindowSize().

Just uses platform-specific ways to do the same thing.
GLX: Remove all Host_GetRenderWindowSize calls.

Also remove x, y, width and height from the GLInterface, since it's only
used in GLX, which no longer uses them