In the end, the API will be released without support for using the SWT version of the Windows API. I got it working pretty well using the DLLs, so it will never be an option to use the SWT version ever again.
Besides the obvious reason for not having to support and waste time a redundant alternative, I have a much more important reason to give up on SWT: the fact that it is not available as a maven dependency in the central repo. That would prevent me from deploying the project in the central.
The next thing I removed completely: any sort of support for XCode. There are just a makefile to handle the whole process, so the build is straight forward: make<enter> from the command line! The make file just requires g++4.2 installed, so it already uses only free and simple tools to build.
The windows DLLs are also buildable from the command line now, but it still requires Visual Studio's installation. In the future, I'll try to build it using mingw to build the DLLs, but I'll certainly leave that for the next version.
Anyway, this sort of stuff is only needed for those wishing to rebuild the native libraries.