Screen: Finish libdc1394 multicamera sync support (Part II).

All hardware trigger control settings implemented and tested:
- Trigger source enumeration, query and select.
- Trigger polarity query and select.
- Trigger mode query and select.
- All sync modes incl. fallbacks: Hardware, Bus, Software.
- Bandwidth query as bonus.
- Improved error handling and also node enumeration.

-> This is relatively well tested and seems to provide resonable
   sync in software mode, where start of master also triggers
   start of slaves by quickly emitting the iso-on commands. About
   < 1 msec error.

-> Both bus sync and hardware trigger sync seem to be sub-msec
   accurate. Microsecond accuracy is expected for hardware triggers,
   but bus sync seems to be also accurate in the low microsecond
   range for cameras of identical model and vendor --> No need for
   external sync cables and trigger inputs if all cameras are identical
   and can be driven from one shared firewire bus (ie. if bandwidth is
   sufficient).

-> Screen for 64-Bit Octave on Linux rebuilt and tested.
-> VideoMultiCameraCaptureDemo updated and tested in various modes,
   also with hardware triggers on identical cameras.