This one was particularly nasty because Windows also defines a DWORD, but in Windows it is an unsigned long, not an unsigned int so changing types caused type conflicts and not all could be removed.
Those referring to the Windows type have to be kept, fortunately they are mostly in the Win32 directory, with a handful of exceptions elsewhere.
- Replaced GTK/OS X (note different from Cocoa) clipboard code with SDL clipboard API.
- Removed requirement to link to GTK in order to compile with GTK support.
- GTK is no longer init'd if the GTK IWAD picker is not used.
- Our usage of GTK is such that the dynamic loader can work with both GTK2 and GTK3 depending on what's installed.
- Since we're accumulating a lot of library loaders I've built a generic interface as FModule which replaces TOptWin32Proc and the loaders in the OpenAL and Fluidsynth code.
The reason for this is that the macOS version uses a deprecated API and in order to correct this, the file needs to be compiled as Objective-C++ which requires a different extension.
