0811 Need to be able to enter descriptive comments and interpretations.

There are often descriptive comments and interpretations. For example, cores have descriptive comments of the lithology, fossils, etc. Furthermore, these comments are versionable. One possibility would be to have a pty_descriptive_comments property (or some other name) which would have as its data_value a long comment field.

Consolidated changes: (0604)

Add pty_descriptive_text and connect to appropriate entities

Add the property pty_descriptive_text to allow versionable descriptions of material_sample, wellbore_interval and wellbore_point. These now all have a new optional attribute called pty_descriptive_text. This is a new concept and requires no migration of existing data.

Added objects:
pty_descriptive_text (Entity)
material_sample.descriptive_text (Attribute)
wellbore_interval.descriptive_text (Attribute)
wellbore_point.descriptive_text (Attribute)