Change representation of clause lists

Amalog doesn't have a native linked list representation.  A more natural
representation is a term with consecutive, integer keys.  This is also
how Lua represets lists using its tables.
Migrate program//1 to use delay//1

This begins the process of making Amalog parsing reversible.
More progress towards reversible parser

This isn't yet completely reversible (being able to generate Amalog
source code from a Prolog term), but it's getting closer.
More accurate name for parsing test

This test is really about parsing Amalog source code into Prolog terms.
The name should reflect that.  There will soon be a separate test of
generating Amalog source code from Prolog terms.
Run parser backwards to generate source code