Set proper values for valves, remove CellValve

Set proper values for valves, remove CellValve

The CellValve is not needed as a separate class, so its only
functionality is absorbed into the Valve class. This is because my
colleague wanted to have the barely open position for the vacuum valve
also and the three-way valve has a closed position in between so the
convention for it is changed and also uses the barely-open argument.

The values for the servos of the valves were measured and so are filled
in the executable.