npc nebula (bit 2.8)

[StarryWisdom]

via mission scripitng I can confirm it looks like npc 2.8 is in a nebula (0=no nebula,nebType1-3=1-3 being set, other values seem to get junk set (but are invalid in mission scripts according to the docs even if they seem to happen on the wire))

suggest we rename it Nebula type (to match pc3.3) and change the comment about 2 bytes to match pc

given that both these where changed in the same update (according to nicks parser only a few fields where changed in one go) it seems highly likely they are identical before.