cleaning up the svn folders/files

[Bjarni]

right now there is os/macos and there will soon be os/morphos too, so why not os/windows
I don't mind the windows project file in the same folder as the source files, but I'm thinking of stuff like the windows installer
It's not a great issue but it will make the code easier to understand for newcommers

[Vurlix]

Done.