Have ZPublisher / PropertyManager handle missing values for "multiple

selection" properties better (ie. default to an empty list, not empty string)

lib/python/ZPublisher/Converters.py

@@ -10,7 +10,7 @@
 # FOR A PARTICULAR PURPOSE
 #
 ##############################################################################
-__version__='$Revision: 1.21 $'[11:-2]
+__version__='$Revision: 1.22 $'[11:-2]
 
 import re
 from types import ListType, TupleType, UnicodeType
@@ -165,6 +165,7 @@ type_converters = {
     'required':           field2required,
     'tokens':             field2tokens,
     'lines':              field2lines,
+    'multiple selection': field2lines,
     'text':               field2text,
     'boolean':            field2boolean,
     'ustring':            field2ustring,