Revert "Project modernization (#630)"

This code was not tested and breaks in Release builds, reverting to restore
functionality of the nightly. All in-game menus do not work and generating
a world crashes.

This reverts commit a9be52c41a.

Minecraft.World/InputStream.cpp

@@ -7,5 +7,5 @@ InputStream *InputStream::getResourceAsStream(const wstring &fileName)
 {
 	File file( fileName );
 
-	return file.exists() ? new FileInputStream( file ) : nullptr;
+	return file.exists() ? new FileInputStream( file ) : NULL;
 }