Restructure the repository to be compatible with 'haxelib git'

The current repository structure is quite a bit different from the structure of the haxelib releases, which makes it impossible to use `haxelib git` for haxeui development. I'm not sure what your current workflow looks like, but this along with all the .bat files in the `/haxelib` makes me think it's not very ideal. How do you test changes to the development version currently? Run the `install-haxelib.bat` every time?

Additionally, this is of course not very welcoming to potential contributors.

The samples no longer use that strange relative pathing (they are there for people to learn from after all, must be rather confusing why the samples differ from other applications in that way). I also got rid of the `build.bat` files and added FD `.hxproj` files instead, making them much more comfortable to work with. FD is pretty much the standard on windows, and `.bat` files are not all that useful on other OS anyway.

In a few of the samples, I'm getting a trace about the "processor for css not being found". Not sure what that's about.