Reorganised the concepts files, moving the Write functions into pmConceptsWrite, and the Read functions into pmConceptsRead, which sort of makes sense. Added new type of concept property: copy. Most concepts use the default copy method (which is to simply copy the item), but for the TIMESYS concepts, we want to ensure that the target is of the correct type --- if it's already set (e.g., via the DEFAULTS), then we don't copy it. This will allow us to set the target TIMESYS using the DEFAULTS in the camera format, and have the output time be adjusted appropriately. Without this, the TIMESYS is simply copied, and specifying the TIMESYS in the DEFAULTS results in a warning ('values don't match'). Removed pmFPACopyConcepts, since it is pretty much the same as pmConceptsCopyFPA.
