Trigger IDs

[nsoblath]

In header: list triggers potentially applied
For each record: word to indicate which triggers were active

[cclaessens]

in the header we need a list of nodes. Every item in the list will consist of a node type (0: event-builder, 1:fmt, aso) and a characterizing parameter (for example: trigger threshold).
The position in the list will correspond to the position in the bit-mask of each record in the file. 0 or 1 at this position will indicate whether the corresponding psyllid node triggered this record.

This needs to be documented (in monarch and the egg file standard).