many small changes, but the two bigger ones are:
* Sensors and controllers now use inheritance, rather than pointing
to the data in a separate struct. Had to add some new RNA define
functionality to support this better.
* DNA_meta_types.h was marked as done but still missing many things,
now completed.
* added rna_property.c and rna_actuator
* enabled access to properties and actuators from object
Note that because we have RNA_Property in the RNA itself, you can find
properties in gamelogic of and object under the name of RNA_GameProperty
