Add beginnings of "New Table" feature

nowhere near complete yet, but skeleton is more or less in place

tailbone/forms/core.py

@@ -1135,6 +1135,8 @@ class Form(object):
         if record:
             try:
                 return record[field_name]
+            except KeyError:
+                return None
             except TypeError:
                 return getattr(record, field_name, None)