Merge pull request #32 from Strigoides/master

Fix COND bug
`defvar` requires two arguments yet
Add !DEFUN and !DEFMACRO macros
These are for defining builtin functions while still being able to test
them in your host CL without conflicting with the existing name.

Say you're defining a builtin function named FOO. If you tried to
compile this function for testing in your host CL, it would throw an
error, as the function already exists and can't be overwritten.
Instead, use (!DEFUN !FOO ...).
The !DEFUN macro automatically performs the rename to FOO when run as
part of jscl, while still allowing you to compile it in your host CL
for testing under the name "!FOO"