BuildSystem: Cleanup userspace directory layout

userspace programs are now in userspace/programs
userspace tests are now in userspace/tests

This makes listing userspace projects much cleaner. Libraries were
already separated to their own directory, so other programs should also.

userspace/programs/Terminal/main.cpp

@@ -0,0 +1,7 @@
+#include "Terminal.h"
+
+int main()
+{
+	Terminal terminal;
+	terminal.run();
+}