Rearranged directory structure a bit. It's now:

lib/
lib/rdl.rb - file to load to get rdl
lib/rdl/ - rdl and types libraries
lib/rdl/types.rb - file to load to get types submodule of rdl
lib/rdl/types/ - types library
lib/types/ - typesigs
lib/types/2.1/ - typesigs for Ruby 2.1
lib/types/2.1/core/ - core library typesigs for Ruby 2.1