Fix some FIXME's

* slime.el
(slime-with-popup-buffer): redesign. Don't take :mode arg.
(slime-popup-restore-data): delete it
        (slime-make-popup-buffer): delete it
        (slime-init-popup-buffer): delete it
        (slime-display-popup-buffer): delete it
        (slime-close-popup-window): delete it
        (slime-save-local-variables): delete it.
(slime-popup-buffer-quit-function): delete it.
(slime-edit-value-callback): don't pass :mode to
slime-with-popup-buffer.
(slime-show-compilation-log): idem
(slime-edit-value-callback): idem
(slime-show-apropos): idem
(slime-create-macroexpansion-buffer): idem
(slime-list-threads): idem
(slime-list-connections): idem
(slime-inspector-buffer): idem
(sldb-setup): no seed to save window-variables.
(sldb-setup): just `pop-to-buffer'
(sldb-debugged-continuations): simplify
(slime-inspector-mode): No need to explicitly list maps in
docstring.
(slime-inspector-mode-map): Override q key using keymaps.

* slime.el: Removed xemacs compatibility layer. Use indent specs.
Don't set `compile-command' file-local var.

* slime.el (slime-with-popup-buffer): Must return current buffer.
(slime-kill-all-buffers): Fix FIXME.
(slime-highlight-differences-in-dirname): Use `split-string' not
`slime-split-string'.

* slime.el (slime-connection): `slime-auto-connect' renamed `slime-auto-start'
(slime-auto-start): Renamed from `slime-auto-connect'
(slime-compile-file-options): Make defcustom
(slime-goto-note-in-compilation-log): Simplify with `cl-loop'
(slime-xrefs): simplify.
(slime-goto-next-xref): Don't use `slime-show-buffer-position'
(sldb-in-face): renamed from `in-sldb-face'
(slime-show-buffer-position): deleted, replaced by `slime-recenter'
(slime-recenter): new function
(slime-save-coordinates): delete it
(slime-coordinates): delete it
(slime-restore-coordinate): delete it
(slime-show-source-location): use `slime-recenter'
(sldb-show-frame-details): don't use `slime-save-coordinates'
(sldb-hide-frame-details): idem
(slime-map-alist): removed
Fix `slime-c-p-c' contrib

* slime-editing-commands.el (slime-close-all-parens-in-sexp): Use
`delete-and-extract-region'. Remove byte-compilation warning.