Fix #2986. Reimplement Metadata property of EPset_Drawing to include arbitrary metadata as CSS classes.

src/blenderbim/blenderbim/tool/drawing.py

@@ -44,6 +44,10 @@ import collections
 
 
 class Drawing(blenderbim.core.tool.Drawing):
+    @classmethod
+    def canonicalise_class_name(self, name):
+        return re.sub("[^0-9a-zA-Z]+", "", name)
+
     @classmethod
     def copy_representation(cls, source, dest):
         if source.Representation: