Remember last UI selection in SConstruct
Commandline history
User ORIGIN in rpath, so that it will still be valid after install
Restructure so that build will fail if primitives are missing from a UI,
and launch will fail if types are missing from a primitive, to make sure
everything is available in all UIs. Add missing stuff to console UI.
Merge functionality from GtkTool into Tool, as it isn't really
gtk-specific
Show what tools are available in console help