Deprecate reversed train variants

[ZeeMaji]

With the reversed trains option being added in 0.4.4 we no longer need the reversed versions of the corkscrew trains & heartline cars as separate objects.

The only issue is backwards compatibility with our old saves using these two objects, but i'm sure we could make ourselves a patched version of openrct2 we could use to fix up any old save files like from when we changed all of the ids last year.