feat: Add new atoms, atoms file and better player movement

[Zac8668]

This adds a lot of stuff!

New material type, that you can modify on the atoms.ron file, that supports hot reloading.
For now you can change the inertial resistance of powders, and change the flow rate of liquids.
The flow changes how fast a liquid spreads, and the inertial resistance changes how likely it is to a powder to spread to the sides

New atoms!
Lava, Water, Dirt, Grass, Gravel and Rock!

You can press:
1 to shoot sand
2 to shoot water
3 to shoot gravel
4 to shoot lava

For Rock and Dirt we need a new precision mode for the tool, as they are solids and do not move and need to be placed in a square or circle shape, and not thrown.

And also, some improvements to the player:

New "states" for the animation, will later be added to a ron or yaml file.
Easier to navigate when using the jetpack.
Now you can hold space to jump higher.

Closes #33