Servo goal value that exceeds max causes parts to get to impossible situations

[adamzl]

If you set the goal value for a servo that doesn't loop (such as the pinch on the claw) the parts will move past the maximums you can attain by using manual controls.

Reproduction:

1. Put a claw on a craft.
2. Click the "All Goal" button.
3. Set the pinch goal field to 0.5.
4. Click the +10 button on the claw's pinch servo a bunch
5. Observe claw's go too far.