
The recipes may be defined by files at two levels: system and camera.

A single recipe (eg, PPIMAGE) must have a system-level file which
defines all of the recipe variables.  The camera-level recipe may
superceed values define in the system-level file.  

Any recipe file may also define alternative symbolic names for
recipes by including metadata folders named by the symbolic name.  

The order of precedence is: 

* primary system-level values
* symbolic system-level values
* primary camera-level values
* symbolic camera-level values

XXX the MULTI RESET thing is broken: the flag is not being carried
through to the psMetadataItemAdd function...

