PAYLOAD STATION NAME should be indexable

[randolf9]

The variable PAYLOAD STATION NAME is defined as a single value, but it should be indexable, same as PAYLOAD STATION WEIGHT.

If I apply this dirty workaround in my code, I can make it indexable and return correct string values, but would be nice to work out of the box:

station_name = aq.find("PAYLOAD_STATION_NAME")
station_name.definitions[0] = (b'PAYLOAD STATION NAME:1', b'String')
station_name.lastIndex = b':index'