BME-46 Fixing the in-world rendering of the waypoint beam

[maddie-j]

This PR just tackles the beam. Label issues are as yet untouched (will focus on next).

Changes:

• Changed so that when close to the waypoint beam, fade it out so it's not in the player's way.
• Fixing the distance at which the beam is rendered if the waypoint is out of render distance,
  • Previous attempt using RenderSystem.getShaderFogStart() put the waypoints all up in your face when moving somewhere foggier like underwater.
  • Now, uses the value that Minecraft uses for shaderFogStart in air specifically. In foggier places, beacon will just be out of view.
  • May return later to put the beam in the fog when shaderFogStart is closer than the now hardcoded value.
• Fixing projected y height of waypoint that's beyond render distance
  • Previously, the distance at which the beam was rendered was measured between the player camera and the waypoint point, meaning the beam rendered closer than expected.
  • Trigged it out so the configured distance is to the waypoint beam, with the waypoint point reprojected onto that beam at the correct angle.