Splinecart v0.0.1-modfest.4 for 1.21

Options for track render distance and track resolution
Reuse cubic spline interpolation for client side position tracking of minecarts on rails, instead of vanilla linear interpolation
Content added by the mod can be crafted and used properly in survival
Track ties and their neighbors behave properly when destroyed
Items have hint tooltips for how to use them, with track items displaying when they have a link to a track tie block
Minecarts no longer stop or stutter when moving from one track segment to another