add uuid type
Revert "add uuid type"

This reverts commit 5fa50673fc074d354edee80fc4eead821067023a.

Need to branch within submodule before making changes.
add uuid type
add port UUID retrieval function
changes to internal client necessary (for now) for UUID changes
add new metadata API header
add jack_client_t* to metadata calls that need to contact the server to initiate a property change callback
add API documentation for some metadata functions
add uuid.h (missed from previous commits)
alter some minor details of the metadata API
alter docs on return value from jack_remove_properties()
wrap UUID generation
__cplusplus-wrap the declarations in uuid.h
add constants for a few (potential) well-known metadata key values
move declarations of client/UUID related functions from session.h into jack.h, since UUIDs are now at the core