checkpoint commit
another checkpoint commit. now mostly using a Body trait. simulation probably doesnt work
move simulation loop code into a separate function
set the force correctly for demo 1
set example 3 force and torque correctly
Merge branch 'master' into new_body
fix a major bug in euler_step for updating the center of mass
add more debug statemetns to euler_step. increase torque in demo1 so its noticeable