Adds F7 Locomotives, minor prop changes and Main Loop track extension

**Added signalling
(Please Note: I am not a train engineer nor educated on the 'correct' way to establish signalling. The signals are placed purely aesthetically, with a 'common sense' approach to placing)
**Replaced some level crossings with new 'bell-less' and barrier-less crossings.

**Added paintable vehicles
** Extended scenery in some sets to acknowledge extended views in miniature

Initial version