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/tools/text/zimwriterfs/default.nix

@@ -8,7 +8,7 @@
 
 , file
 , icu
-, libgumbo
+, gumbo
 , lzma
 , xapian
 , zimlib
@@ -27,7 +27,7 @@ stdenv.mkDerivation rec {
   };
 
   nativeBuildInputs = [ automake autoconf libtool pkgconfig ];
-  buildInputs = [ file icu libgumbo lzma zimlib zlib xapian ];
+  buildInputs = [ file icu gumbo lzma zimlib zlib xapian ];
   setSourceRoot = ''
     sourceRoot=$(echo */zimwriterfs)
   '';