replace unqualified core forms with qualified version and macro

[felix winkelmann]

These special forms should be replaced with macros that expand to qualified forms:

if
quote
syntax
let[rec]-syntax
foreign-[safe-]lambda[*]
define-constant
location

These should be then removed from canonicalization (with qualified versions remaining):

begin
let
letrec
lambda
set!

This should also take care of #18.

[felix winkelmann]

In commit 9767d784c45621732bbdd080260cfc011cd5da7b,

• define-compiled-syntax bas been deprecated
• define-syntax has been replaced by core syntax and a qualified internal form

[felix winkelmann]

Added aliases and internal forms in 9c60c5c (experimental) for:

define-foreign-type
define-external-variable
foreign-primitive