fixed bug in flat loader initial agent building loop
removed in/out commods from facility class.  They will still be in input files.  If agents want to access them, they can do so directly themselves.
* added Flush method to recorder used by file loaders to update querybackend
  with barely-dumped data.

* DbInit and file loaders inject a 'AgentState_' prefix for all agents in their
  infile->db and db->agent init methods

* added Lifetime col to AgentEntry table.

* implemented model class's InitFrom(Querybackend) and InfileToDb methods.

* Added prefixInjector for queries to add table prefix automatically.
implemented agent initialization in sim_init.  I'm not sure if it works correctly yet.
todo list
* Implemented resource snapshot and unloading.

* implemented simulation snapshotting via context::Snapshot()

* Created DoRegistration method where agents should do all registrations.
  Model::Build method calls DoRegistration. No registrations should occur from
  Build methods. This allows reregistering for sim restart/init without having
  to call the build method ever more than once. Agents are responsible for
  tracking their (un)registered states.

* Added NextIds tracking table for persisting/loading static next id vars

* Removed units from generic resource. Cyclus resources should have a single
  unit per resource type - that is how the core treats all resources for
  resource exchange and elsewhere.

* Added extra MaterialInfo table to record/reload misc internal state not
  already in output db

* Added extra GenericResource table to record internal state - state ids and
  qualities. Added next_state_ static var to track Gres state ids.
Added support for translating initial inventories to output db