Only initialise PyKoki once, not for every frame
Include all details in messages

Messages and topics have been renamed to provide a better indication of
what they contain, and to have consistent capitalisation.

All details provided by libkoki are now given in the KokiMarker message.
The geometry_msgs package is used where possible.

The print_tokens launch file and script now displays information from
the koki_markers topic.
Change marker size, show distance in print_tokens
Tidy up code
Rename roskoki2.py and the roskoki class