Add script to turn players into meshes, ticks every 1 second

Trigger the player.lua file in init.lua

Commit the ugly and temporary test model and texture. We'll get to a real animated player mesh once the code for that is ready

Set visual_size accordingly so the player model doesn't stretch vertically (default of the sprite player)

Attempt to use the b3d model format, although it doesn't seem to work so far