[urxvt] Remove “URxvt.perl-lib” from resources

rxvt-unicode already looks for extensions in ~/.urxvt so there is
no need to explicitly specify that directory in resources.
[emacs] Fix checkdoc warnings.
[emacs] Use `eval-and-compile' instead of duplicating code
[emacs] Remove Marmolade and ignore Wiki packages

Wiki packages are built from EmacsWiki which has no access
control and *anyone* can edit the code potentially including
harmful code.
[emacs] Rewrite and better document `set-key'.

Also add :global keyword for explicitly specifying global
keymap which allows use of symbol as a key, as in
    (let ((key (kbd "a")))
      (set-key :global key self-insert-command))
[emacs] Bind C-d to DEL so that both respect `delete-active-region'

In default bindings, C-d is bound to `delete-char' which, contrary
to `delete-forward-char' does not respect `delete-active-region'
or `overwrite-mode'.  Fix that.
[emacs] Remove invalid `comment-dwim' binding.

`comment-dwim' is available under M-; anyway.
[emacs] Minor style fixes.
[emacs] Set up minibuffer bindings for C-p/n to browse history.

It's not clear to me what other use C-p and C-n may have in
minibuffer which is single line anyway.  Instead make those
key behave in some sane way and show history elements.
[emacs] Better check programming modes in `mn-turn-flyspell-on'

Use `derived-mode-p' instead of trying to list existing programming
modes.
[emacs] Compilation fixes for mail.el.
[emacs] Remove unnecessary autoload.