The Big commit ®:
- Removed all the stuff that is unneeded on the clips thread-storage
(everything except the view parameter)

- Removed all the stuff that was pre-fetching RoDs and stuff prior to
instanceChanged

- make getRoD be callable recursively

- Speed-up the parameters refreshing
Merge branch 'workshop' of https://github.com/MrKepzie/Natron into workshop
Fix compilation with boost 1.56