Rename Idle state to Sit state

[mike4192]

Rename idle state to sit state to more accurately represent it

[sbias]

In my opinion, the current idle-pose is not sit, but down. For a command named sit i'd expect more a pose like this:

Maybe idle is more a laydown with servos off after transition :)

[mike4192]

Yes I agree, something like lie down is more appropriate.

[sbias]

just noticed that idle is disabling the servos already, so, i think idle is absolut correct for this action.