Active light master limit may be too generous

[Ortham]

The Creation Kit wiki page on the file formats says that

A maximum of 4096 .esl files can be loaded by the engine at once, but more Form IDs in an .esl file means that less .esl files can be loaded. Using .esl files that each have 2048 Form IDs, the limit drops to about 300 loaded .esl files.

libloadorder currently just uses a static 4096 as the max, because I don't understand the relationship between number of FormIDs and the maximum active light masters, but filing this issue in case it gets figured out or more is revealed in future.