Used fixed point arithmetic in energy & health

[Indy2222]

For the sake of determinism: for example float addition is not commutative due to precision issues.

Idea: implement a simple fixed point type in de_types which uses i32 as the storage. Use ~10 bits for fractional part. Ensure that the minimum and maximum representable value is small / large enough for the game purposes.

[github-actions]

There is no activity on the issue for some time.