Neo Elytra Flight HUD

This mod adds a heads-up display to the Elytra.  It is a fork of the [Elytra Flight HUD](https://www.curseforge.com/minecraft/mc-mods/elytra-flight-hud) mod with the 3D projection corrected and some little features added. Metric units are now used – speed is shown in km/h and vertical speed in m/s. The mod is currently incompatible with "do a barrel roll" due to disregarding the camera's roll.