Support for Huber chillers with ComGate interface
Implementsd a new class to communicate to Huber chillers with ComG@te interface. This is in addition to the existing Huber chilleer class due to the different interface and thus different command set. Documentation: https://www.huber-online.com/download/manuals/archive/unistats_EN.pdf (pp 83-86 describe the communication).
Tested on Goettingen's Huber Unistat 705 with ComG@te interface via RS232.
2nd try, based on the current devel branch to avoid the trouble with an Agilent class seen before.