Allow annotations on modules

[jtoman]

Currently Rtc allows only the annotation of classes. It should also allow the annotation of modules. This will also let us do the following:

class IncluderClass
    include :module1,:module2,...
end

The includes will look up the modules, and for each module add the method annotations of that module to the current class (or theoretically, another module). Different handling for conflicting signatures will be required for this to work. That is, if module Foo defines a method bar with some signature sig₁ and class A also defines bar with signature sig₂, and A includes Foo, then the signatures sig₁ and sig₂ should not be automatically intersected, but rather the signature from A should overwrite the signature from Foo.

[jtoman]

self annotations on modules currently work. In addition it'd be nice if we could use modules as names in the grammar, so that a method would accept only objects whose class includes the some specified module (see the set class for a use case for this).

[jtoman]

A neat feature would allow polymorphic mixins. Something like this:

module MyPolymorphicMethods
   rtc_annotated [:t]
   typesig("test_element: (t) -> %bool")
   # ....
end
class Foo
   rtc_annotated [:k, :each_key]
   include MyPolymorphicMethods
   rtc_includes :MyPolymorphicMethods, :t => :k
end

Which would include all the methods from MyPolymorphicMethods but replace all instances of t in the typesigs with k