FR K2 Class Mixed-traffic Engine

This may be the final revision.

Differences are noticeable so a list isn't required.

It's been fun working on it, but I cannot see how I could improve the design without starting from scratch.

Final brick count: 393 (tracks excluded)

Changes:

+ Colour scheme has been improved

+ The gap between the Firebox and Water Tank is partially fixed

+ The Tender got a redesign and now holds "coal"