Custom Agenda Commands / Property Overhaul

Added custom agenda commands to be able to view task classes as tables
in agenda view and global TODO view using properties. To accomplish
this, properties needed to be standardized.

Everything is still on paper in my apartment, but eventually I’ll write
a guide that goes with all of it.

Long story short, there are now four TODO sequences:
1) TASKS
2) POSSESSIONS
3) MULTIMEDIA
4) EVENTS

Each class, regardless of the number of TODO states in each individual
sequence, has the same properties.

In addition, non-todo states (:fin: for financial and :note: for note)
now have capture templates and properties that match their todo state
counterparts. The custom agenda views added support viewing both todo
and non-todo states, even for inactive timestamps when appropriate.

to-do-states.el should probably be renamed to todo-states.el. Oh well.
Next time.

Everything in my individual org-files still needs to be updated, but
these changes should work with the most recent version of org.