Exit fullscreen if focus is changed to a window on the same monitor even with multi-monitor setups.

This commit reverts 7e22ddca36d0556f8ef30cc8cae1aab40b746cba.
VideoRenderers: Use a focus window in D3DFullscreen.

Also, don't allow D3D to change the window style. This fixes the loss of focus when D3DFullscreen is active.
FullscreenWnd: Send thumb mouse buttons to MainFrm.
MainFrm: Exit D3DFullscreen at the end of playback if enabled in the options.
MainFrm: Don't open the popup menu behind D3DFullscreen.
MainFrm: Only start in D3DFullscreen if we closed it, remembered it or indicated it on the command-line.
VideoRenderers: Put D3D Focus Window in separate thread.
FocusThread: Reduce flickering by ignoring WM_NCACTIVATE messages.
MainFrm: Don't create a D3D object when adapter is in exclusive mode.
MainFrm: D3D overrides our display mode, so we can't apply the default before we exit D3DFS.
FocusThread: Give focus back to MainFrm.
DX9AllocatorPresenter: Check for 10-bit device support before enabling m_bHighColorResolution.
Updated changelog