(nsm-check-protocol): Check for weak Diffie-Hellman prime bits.

Fixes: debbugs:19153
* lisp/emacs-lisp/avl-tree.el: Use lexical-binding and cl-lib.

(avl-tree--root): Remove redundant defsetf.
Fatal GnuTLS errors are now silent by default

Fixes: debbugs:16253

(emacs_gnutls_handle_error): Fatal errors should be on level 1, so
that they are not messaged by default.
Various minor details accumulated over time

* lisp/info.el (Info-mode-map): Remove left-over binding.
* lisp/net/tramp.el (tramp-handle-make-symbolic-link): Mark unused arg.
* lisp/obsolete/gulp.el (gulp-create-m-p-alist): Remove unused var `mnt-tm'.
* lisp/progmodes/gud.el (gud-gdb-completions): Remove unused var `start'.
* lisp/url/url-http.el (url-http-activate-callback): Make debug more verbose.
* src/process.c: Whitespace and line-break nitpicks.
(Fgnutls_error_fatalp): Doc fix (bug#18210)

Fixes: debbugs:18210