gui: remove bitmapFromMem macro

Not needed anymore and this is in wxWidgets upstream meanwhile.

re #222

src/gui/bitmapFromMem.h

@@ -1,19 +1,10 @@
 #ifndef BITMAPFROMMEM_H
 #define BITMAPFROMMEM_H
 
-#include <wx/mstream.h>
 #include <wx/bmpbndl.h>
 #include <wx/filename.h>
 #include <wx/stdpaths.h>
 
-#define bitmapFromMem(name) _GetBitmapFromMemory(name, sizeof(name))
-
-inline wxBitmap _GetBitmapFromMemory(const unsigned char *data, int length) 
-{
-   wxMemoryInputStream is(data, length);
-   return wxBitmap(wxImage(is, wxBITMAP_TYPE_ANY, -1), -1);
-}
-
 #define bitmapBundleFromSVGResource(name) wxBitmapBundle::FromSVGFile(wxFileName(wxStandardPaths::Get().GetResourcesDir(), name, "svg").GetFullPath(), wxSize(24,24))
 
 #endif