Fix thumbnails by adding missing border pixels

[spacek531]

RCT1 sprites had the border gradient baked into the sprite. This ideally should be reversed, likely manually in some cases where prototype graphics are used.

List of thumbnails not yet converted as of this writing:

• rct1.ride.chairlift_cars
• rct1.ride.corkscrew_trains
• rct1.ride.dignhies
• rct1.ride.dodgems
• rct1.ride.logs
• rct1.ride.mine_trains
• rct1.ride.mouse_cars
• rct1.ride.reverse_freefall_car
• rct1.ride.small_monorail_cars
• rct1.ride.sports_cars
• rct1.ride.stand_up_trains
• rct1.ride.steam_trains
• rct1.ride.steel_rc
• rct1.ride.suspended_swinging_cars
• rct1.ride.vertical_drop_trains
• rct1.ride.wooden_rc_trains
• rct1aa.ride.bicycles
• rct1aa.ride.flying_saucers
• rct1aa.ride.mini_helicopters
• rct1aa.ride.reverser_cars
• rct1aa.ride.side_friction_cars
• rct1aa.ride.splash_boats
• rct1aa.ride.steel_wild_mouse_cars
• rct1aa.ride.twister_trains
• rct1aa.ride.wooden_articulated_trains
• rct1ll.ride.4_across_invert_trains
• rct1ll.ride.air_powered_trains
• rct1ll.ride.coaster_boats
• rct1ll.ride.inverted_hairpin_cars
• rct1ll.ride.rafts
• (lay-down coaster)
• (river rapids)
• (virginia reel)

[ZeeMaji]

One useful thing to note is that some of the thumbnails were taken from pre-built rides in some of rct1's scenarios, mainly megaworld park from what i remember.
Here's three examples from megaworld park that i noticed.






Granted some of them seem to have changed during the window between RCT1's pre-release development and LL's release which included megaworld park as some of the ride colors are different and there's a missing tree in the megaworld bobsleigh but they should still prove to be very useful for reconstructing the original thumbnails without the pre-baked border gradient.

[spacek531]

More megapark screenshots