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.Client/FileTexturePack.cpp

@@ -36,7 +36,7 @@ InputStream *FileTexturePack::getResourceImplementation(const wstring &name) //t
 
 	return zipFile.getInputStream(entry);
 #endif
-	return nullptr;
+	return NULL;
 }
 
 bool FileTexturePack::hasFile(const wstring &name)