* slime-tests.el (require): Add necessary require statements to
avoid warnings. Don't use xemacs compatibility layer.

* slime.el (slime-require): Move up to avoid byte-compiler warning.
(slime-setup, slime--setup-contribs): Use `slime-contribs'
directly.
(sldb-in-face): Renamed from `in-sldb-face'. Rename in users.

* lib/hyperspec.el: Require `cl-lib' instead of `cl'.

The contrib's Makefile now works as the top-level Makefile,
byte-compiling files separately, uncovering errors when trying to
byte-compile files in isolation. Fixed almost all such problems in
contrib's el files and remove uses of the "xemacs compability layer",
in preparation of its removal.

For most files this amounted to moving some definitions around,
requiring the needed libs at the top, and prefixing cl-lib functions
with "cl". `cl' is required at compile-time only for macros which
aren't found in cl-lib.

In slime.el, slime-tests.el and lib/hyperspec.el a few tweaks also
removed the last f...