Polish, fix and otherwise improve the video plugin configuration dialog:

- Add some info about a backend's feature set (MSAA, Real XFB, EFB to RAM, ..) to VideoConfig
- Gray out options if they aren't supported by the backend or if changing them doesn't affect anything (e.g. changing STC mode if STC is disabled)
- Allow signed bytes for D3D11. Not sure if this causes glitches, but it should work
- Call wxEvent.Skip() in the event function handlers, not sure if this fixes any bugs but the old code definitely caused bugs during development of this patch
- Fix a memory leak in the configuration dialog if D3D11 is used
- Other minor stuff that doesn't need to be mentioned or which I forgot

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@6450 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Core/VideoCommon/Src/VideoConfig.cpp

@@ -34,11 +34,17 @@ void UpdateActiveConfig()
 VideoConfig::VideoConfig()
 {
 	bRunning = false;
-	bAllowSignedBytes = !IsD3D();
-	
+
 	// Needed for the first frame, I think
 	fAspectRatioHackW = 1;
 	fAspectRatioHackH = 1;
+
+	// disable all features by default
+	backend_info.APIType = API_NONE;
+	backend_info.bAllowSignedBytes = false;
+	backend_info.bUseRGBATextures = false;
+	backend_info.bSupportsEFBToRAM = false;
+	backend_info.bSupportsRealXFB = false;
 }
 
 void VideoConfig::Load(const char *ini_file)