Takes telescope out of the Parked state.
ASCOM.DriverAccess (in ASCOM.DriverAccess.dll) Version: 3c9121baba46811fe6e53a58a05935662261416d
The state of Tracking
after unparking is undetermined.
Valid only after Park
Applications must check and change Tracking as needed after unparking.
Raises an error if unparking fails. Calling this with AtPark
= False does nothing (harmless)