Remove spaces for dictionary short names

media kind "Descriptive Metadata" has a space in some files

src/aaf2/dictionary.py

@@ -13,6 +13,7 @@
 from .utils import register_class
 
 def short_name(name):
+    name = name.replace(" ", "")
     for s in ('DataDef_', 'ContainerDef_'):
         name = name.replace(s, "")
     return name