Hip joint collisions

[robEllenberg]

The hip joint limits vary widely depending on the pitch and roll of the joint. For extreme swings of the legs, the pitch and roll limits of the hip are not valid. While each pitch and roll limit is independently valid, when the leg is raised forward, the roll range of motion is less than half of the initial limit, and vice-versa.

[robEllenberg]

Closed as redundant with #36