Corrected def-phys-const macro. (pass doc-string to defparameter only when non nil).
Corrected def-phys-const macro. (pass doc-string to defparameter only when non nil).

informatimago/lisp,informatimago/lisp,informatimago/lisp,informatimago/lisp,informatimago/lisp,informatimago/lisp,informatimago/lisp