[x] Refactor Accessory: add classes for different accessories: generic accessory, aperture, pol/depol
if the information about whether pol or depol mode is used in Pol/Depol accessory is available in the .asc file, read it and populate the quantity PolDepol.mode:
Hiroki confirmed that the instrument software is not aware about if this accessory is used or in which mode it is used. So the information is not available in the .asc file.