Patch to fix tikz-uml for PGF 3 (see http://tex.stackexchange.com/questions/263174/undefined-control-sequence-error-when-using-tikz-uml-package-in-latex)

tikz-uml.patch

--- tikz-uml.sty.orig   2015-10-10 23:44:04.978866966 -0300
+++ tikz-uml.sty    2015-10-10 23:29:46.902834319 -0300
@@ -16,7 +16,7 @@
 \RequirePackage{xstring}%
 \RequirePackage{calc}%
 \RequirePackage{pgfopts}%
-\usetikzlibrary{backgrounds,arrows,shapes,fit,shadows,decorations.markings}%
+\usetikzlibrary{backgrounds,arrows,shapes,fit,shadows,decorations.markings,math}%

 \def\tikzumlPackageLayersNum{3}%
 \pgfkeys{/tikzuml/options/.cd, packageLayers/.initial=3}%
@@ -626,7 +626,11 @@
   \setcounter{posT}{100*\real{\positionT}}%
   \setcounter{posStereo}{100*\real{\positionStereotype}}%
   %
-  \pgfmathsetmacro{\weightT}{1-\real{\weight}}%
+  % \pgfmathsetmacro{\weightT}{1-\real{\weight}}%
+  \tikzmath{%
+      real \weightT;%
+      \weightT = 1 - real \weight;%
+  }%
   %
   \def\tikzumlControlNodesNum{0}%
   %