Direction of sweep is inconsistent between ANALOG OUT and FAST OUT

[bleykauf]

When switching between sweeping using laser current via FAST OUT and sweeping the piezo voltage (of an ECDL) the spectrum is mirrored, i.e. it behaves as if the direction of the ramp is changed. I think it was better if the direction of the slow ramp would be opposite for the piezo ramp.

This might be different depending on the setup. However, this should be user configurable, e.g. by using the polarity of the outputs under the slow control settings.