Shorten parameter names to NNPFC to save space in user manual (an maybe make them easier to type).

No specific table formatting is required for NNPFC anymore.

- Add the control for that flag in the cfg file & update the manual doc
- Implement checking at encoder side to ensure that when sending an update the base filter is already present
- Implement detection at decoder whether the given base filter is a new or a repetition filter.
- Implement checking at decoder side to ensure that when receiving an update filter, the base filter has been received earlier / already present.

prefix byte