added do-macro to toplevel, but only tested with R5RS example so far (issue 56)
added do-macro to toplevel, but only tested with R5RS example so far (issue 56)

aisamanra/owl-lisp,yuriy-chumak/OL,yuriy-chumak/OL,yuriy-chumak/OL,aisamanra/owl-lisp,aoh/owl-lisp,yuriy-chumak/OL,aisamanra/owl-lisp,aoh/owl-lisp,yuriy-chumak/OL,aoh/owl-lisp,yuriy-chumak/OL