New map, small Wedge fix

Added a new map, Indra, which is a "remix" of Harha from Fosfori.
Model updates, fixes for hector
Added an RK4 integrator class that is now being used for hector gravity.
Modified integrator to use vectors and points.
Got friction working kind of. It should be a per PhysicalObject thing, but hectors do not currently know what they are walking on, so that's going to be a bit more involved.
merging pov's physics updates
I think this is closer to realistic friction
The hectors XZ velocity should be adjusted when hitting a wall, so that the hector will not slide around corners on slippery surfaces or change direction in midair if a jump includes sliding off a wall.
In order for it to be easier to jump onto blocks from right in front of them, there is a tiny amount of friction in air so you can kind of move in air. Apparently avara did this?
Merge https://github.com/jonathanvoss/pavara
added 3d sound demonstration with incarn sound and footstep sound (camera is frame of reference)