Log Message:
Update to guile 1.6.3.

** GOOPS longer creates layout entries for non-instance slots.

** syntax-case bugs have been fixed

   a) Macro expansion is no longer disturbed if the value of
      (current-module) changes.  This was the cause of a number of
      different bugs people have reported.

   b) Syntax-case now expands Guile's own macros as a part of the
      macro expansion process.  Previously, Guile macro calls were
      treated as applications.

   c) Objects which are constant data and which Guile considers
      self-evaluating are no longer quoted.

   One good consequence of these fixes is that it's now possible to
   use syntax-case macro expansion together with GOOPS code.

** scm_readline now checks that it's using an output (not input) port.