Fix: trains cancelling their pending reversal when ordered to go to a depot behind them

Previously, if a train had been ordered to reverse, and while it was slowing down, was
ordered to travel to a depot that is behind it, the train would continue forwards.
Also when a train had been ordered to reverse, and while it was slowing down, was
ordered to travel to a depot that is in front of it, the train would not cancel the
reversal.
In both cases the train would travel away from the target depot.

Trains in this situation now behave correctly and will travel towards the depot.

Feature: Group liveries, and livery window usability enhancements. (#7108)

* Change: Replace checkbox in livery selection window with Default option in drop down selection.

This reduces clutter in the UI and allows for primary/secondary colours to independently follow the default scheme if desired.

* Feature: Add vehicle group liveries.

Fix: Some code and comment typos

Found with codespell

Feature: Framerate display window (#6822)

Frame rate and various game loop/graphics timing measurements and graphs. Accessible via the Help menu, and can print some stats in the console via the fps command.

(svn r25226) -Fix/Change [FS#5538]: [NewGRF] Revise when vehicle running sound effects 04, 07 and 08 are played.
In depot or tunnel, or when crashed or stopped: No sound.
Braking: Effect 08 instead of 07.