Where checking if value is in enum will raise value error in Py38

* Added driver/motor tables for T/KDC001 APT devs.

* Moved TODO comment to avoid pylint error.

* Misc Py3k changes for ThorLabs APT

* motion_timeout for APT motor cmds, fix scale factor

* ThorLabsAPT: Example of new config support.

* More pylint fixes

* Fix for line continuation convention.

* Rearranged imports into standard order.

* Added an APT test. Not working yet.

* Fix linting issues

* New handling in loopback for empty terminator.

* struct.Struct for contents of hw_info packets

* Support for specifying expected apt pkt sizes

* Fixes to APT and APT tests

* Missed a conflict marker.

* Fixed bug due to `if size` falling through on size == 0.

* Removed trailing whitespace.

* Locked requirements.txt; see #174.

* Remove numpy version pinning in requirements.txt

* Add tests to cover additional loopback comm behaviour

* Make pylint happy

* Revert changes to size=0 behaviour in loopback comm

* Fix bug with SCPIFunctionGenerator.function, add tests

* Fix linting

* Function Generator single/multi-channel consistency

* Fix Py27 linting issue

* Fix linting issue

* Add tests for FunctionGenerator abstract instrument

* added mhs5200

* added minghe function generator

* added absolute_import

* fixed scaling on frequency

* switched to abstract instrument class

* fixed a few docstrings

* after testing with device

* Minghe MHS5200 - Add instrument to docs

* isolating changes from cc1 test station:

* Revert "isolating changes from cc1 test station:"

This reverts commit 87b8dec.

* reverting changes and fixing duty cycle

* Update for new FunctionGenerator multichannel consistency update