Servo Enstop Jitter fix, Detach servo pin after moves

This code change allows an additional delay time to keep the servos energized long enough to complete the angle change from and from the engaged position to retracted position. Alleviating the jitter from lost pulses this way only covers up the issue, but it goes a long way towards making this a much nicer feature. This patch doesn't clean up any of the Auto Bed Leveling code that does a similar thing. So, with this feature and Auto Bed Leveling enabled the servo will be attached/detached twice. I have contacted the original commiter @alexborro about this and will coordinate with changes to remove redundancies.