There's not many useful things we can do with this log, other than
providing a way for downstream applications to identify those logs.

For a lot of applications, it can be useful to distinguish between logs
made in raids, fractals, ...

Note that we probably don't want further categorization (as for example
done in ezau).

The wording on the evtc README is

> an npcid of 1 indicates log is generic - triggers by squadmember
> entering combat and not as a result of a boss species id.

It is not quite clear whether "generic" implies WvW or if there are PvE
generic logs as well if you manage to set up arcdps in the right way.
Therefore, the wording in evtclib is rather unspecific as well.

This is the first step in differentiating between Encounters and Bosses.
It sounds a bit weird at first, but there are some events without any
bosses (like the River of Souls), and some events which have multiple
bosses (like Twin Largos or the kodan strike mission). If we want to
support this better, without relying on extra IDs, special casing and
constants (like NIKARE_ID), we should differentiate between Encounters
and Bosses.