Obs should have a pointer for the form_field it was created through

It is impossible to reliably determine exactly which form field an obs was created through. (For simple forms you can guess correctly 100% of the time, but for complex forms, where more than one field has the same concept or concept_set, it's impossible to get it exactly right all the time.) This makes it impossible to reliably re-display a form "as entered". It also means that there's no way to tell from an obs exactly what text was associated with the question asked on the form.

We should add a form_field column to the obs table.

As a consequence, we'd need to update the formentry and xforms modules to carry this information through. (At present htmlformentry does not use the form schema tables, but once it does, it should support this too.)

TODOs:

Add to Obs:

• void setFormField(String namespace, String formFieldPath);
• String getFormFieldNamespace();
• String getFormFieldPath();

This should be done in a branch or create a patch so that it doesn't get into trunk until we have other obs-table-related changes.