Suggestion: make it possible research track electrification in custom researches.

[scailman]

It would be nice to be able to create custom researches of certain items such as track electrification that doesn't rely on current researches even though two researches unlock the same item.

It would give more freedom when unlocking buildings, industrial vehicles etc.
Currently you can research almost everything but it is based on sets of individual assets, not on a part of an asset such as the track electrification.