Added referral entity. Timestamps for patient history events.

Also, a patient is a person (one-to-one).
File upgraded to version 1.0.7 of Power Architect.
Updated design PDF to latest version.
Small database revamp, added missing features as discussed.

Fixed a few primary keys that were not set as autoincrements.
Added alt_name to fiscal data in case patient is invoicing in favor of another person.
Remedies can now be related to a given patient.
Referrals support (new type imr_referral_type).
Removed parent_inst_id from categories; it's redundant.
Updated exported imr.sql location to Power Architect 1.0.7's new default.
Removed unneeded imr.sql export file. This is a transient file.
Added background info to patients.