Merge pull request #1 from Galvant/dev

Pull from upstream
Added start of work on Newport ESP-301 class.
Merge branch 'dev' of github.com:cgranade/gpibusb-comm_code into dev
Continued work on Newport ESP-301 controller driver.
Fixed stupid bugs.
Added new documentation, new methods to Newport ESP-301.
Continued work on ESP-301.
Merge pull request #2 from Galvant/dev

Pull from upstream
Started work on SRS DG645 communications.
Fixed misc bugs.
More bugfixes. Something about baud=3.
Fixed remaining problems to connect to DDG.
Added delay functionality to SRSDG645.

Very rough so far... need to clean up documentation and imports.
Added one new property.
Merge pull request #4 from cgranade/dev

Merged bug fixes, two new instruments