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

doc/default.nix

@@ -16,7 +16,7 @@ pkgs.stdenv.mkDerivation {
   # $ nix-shell --run "make clean all"
   # otherwise they won't reapply :)
   HIGHLIGHTJS = pkgs.documentation-highlighter;
-  XSL = "${pkgs.docbook5_xsl}/xml/xsl";
+  XSL = "${pkgs.docbook_xsl_ns}/xml/xsl";
   RNG = "${pkgs.docbook5}/xml/rng/docbook/docbook.rng";
   XMLFORMAT_CONFIG = ../nixos/doc/xmlformat.conf;
   xsltFlags = lib.concatStringsSep " " [