treewide: remove aliases in nixpkgs

This makes the command ‘nix-env -qa -f. --arg config '{skipAliases =
true;}'’ work in Nixpkgs.

Misc...

- qtikz: use libsForQt5.callPackage

  This ensures we get the right poppler.

- rewrites:

  docbook5_xsl -> docbook_xsl_ns
  docbook_xml_xslt -> docbook_xsl

diffpdf: fixup

pkgs/development/libraries/gtkd/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchzip, atk, cairo, dmd, gdk_pixbuf, gnome3, gst_all_1, librsvg
-, pango, pkgconfig, substituteAll, which }:
+, pango, pkgconfig, substituteAll, which, gst_plugins_base }:
 
 stdenv.mkDerivation rec {
   name = "gtkd-${version}";