Make xhtml2pdf its own package in python-packages

xhtml2pdf now uses the main package html5lib with just an override to
pull the correct version number.

pkgs/development/python-modules/xhtml2pdf/default.nix

@@ -0,0 +1,33 @@
+{lib, fetchPypi, buildPythonPackage, html5lib, httplib2, nose, pillow, pypdf2, reportlab}:
+
+let
+  #xhtml2pdf specifically requires version "1.0b10" of html5lib
+  html5 = html5lib.overrideAttrs( oldAttrs: rec{
+    version = "1.0b10";
+    src = oldAttrs.src.override {
+      inherit version;
+      sha256 = "1yd068a5c00wd0ajq0hqimv7fd82lhrw0w3s01vbhy9bbd6xapqd";
+    };
+  });
+in
+
+buildPythonPackage rec {
+  name = "${pname}-${version}";
+  pname = "xhtml2pdf";
+  version = "0.2.1";
+
+  buildInputs = [html5];
+  propagatedBuildInputs = [httplib2 nose pillow pypdf2 reportlab html5];
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "1n9r8zdk9gc2x539fq60bhszmd421ipj8g78zmsn3njvma1az9k1";
+  };
+
+  meta = {
+    description = "A pdf converter for the ReportLab Toolkit";
+    homepage = https://github.com/xhtml2pdf/xhtml2pdf;
+    license = lib.licenses.asl2;
+    maintainers = with lib.maintainers; [ rprospero ];
+  };
+}