Create an "Extended Zylisp"

[oubiwann]

Zylisp core defines a small set of functions (and takes advantage of all the Go functions). There's not much to the "Core Zylisp" as a Lisp, though ... it's more like a quasi-proto-scheme.

An "Extended Zylisp" would:

• Be written in Core Zylisp
• Provide a macro capability (and related functions)
• Provide language-level macros like defn, cond, etc.
• Provide a means of interning these to match "Core Zylisp" usage
• Define an eval function
• Provide a series of transpiling functions for converting "Extended Zylisp" to any of "Core Zylisp", Go AST, Go source code, or Go bytecode.