Problem:    Cannot call a :def function with a number for a float argument.
Solution:   Accept a number as well, convert it to a float.

Problem:    Getting interface member does not always work.
Solution:   Convert the index on the interface to the index on the object.
            (closes #11825)

Problem:    Interface of an object is not recognized when checking type.
Solution:   Use the interface implemented by an object.

Problem:    A child class cannot override functions from a base class.
Solution:   Allow overriding and implement "super".

Problem:    Extends argument for class not implemented yet.
Solution:   Basic implementation of "extends".

Problem:    Class "implements" argument not implemented.
Solution:   Implement "implements" argument.  Add basic checks for when a
            class implements an interface.

Problem:    Build failure.
Solution:   Add missing part of :interface change.

Problem:    Class members may be garbage collected.
Solution:   Mark class members as being in use.

Problem:    Cannot call an object method in a compiled function.
Solution:   Compile the instructins to invoke an object method.

Problem:    Class function not implemented yet.
Solution:   Implement defining and calling a class function.