Generic mechanism for doing Attributes and Attribute Types on many classes. (Review code, and Refactor.)

In 1.9 we're introducing a new generic mechanism for doing attributes. This ticket is a placeholder for the fact that we have to review this code (and likely refactor) before we release 1.9. Please let's keep significant design discussions on the mailing list rather than having them on this ticket.

Newly added:

• Visit Attributes (in trunk)
• Location Attributes (in trunk)
• Provider Attributes (providers branch)

Based on 1.8: (use datatype and config_handler)

• Person Attributes (in branch ImprovedPersonAttributeType)

Related:

• new work on Complex Obs (by Suranga in branch : http://svn.openmrs.org/openmrs/branches/obs-codes-expanded)

Helpful links :

The discussion on converging data types :
https://wiki.openmrs.org/display/docs/Converging+on+Custom+Datatypes+(Design)

Detailed Discussion on converging between Ben / Burke / Darius in the second half of this e mail
http://openmrs-mailing-list-archives.1560443.n2.nabble.com/Design-issue-Our-setter-methods-td6548679.html#a6584634

Documentation on Obs handlers can be found under this
https://wiki.openmrs.org/display/docs/Complex+Obs+Support (there are several pages)