Guided decision table: Pluggable editors for (Business) Model Fact Types

Only pop-up editors for a small range of data-types are currently supported (e.g. numeric, Date, Boolean, String, enum). Add support for pluggable "pop-up" editors (possibly look at integrating WorkingSets' custom forms?). An example would be "Post Code", "National Insurance Number", "email address" etc where they are "single-field" but require their value to follow a well defined pattern.