Variable Gravity

[giovaniceotto]

Everything changes in RocketPy... but for some reason, the gravitational acceleration is constant.

For higher altitude flights, this is no longer acceptable.

This issue requests a variable gravity model.

Requirements

1. Accurately model the gravity variation as a function of altitude.

2. Accurately model the gravity variation as a function of latitude/longitude (optional).

3. Have no significant impact in simulation time.

Proposed Milestone

v1.0.0

[MateusStano]

Solved in #338