Merge pull request #6 from Galvant/dev

Pull from upstream
Continued refactoring into ProxyList, nicer properties.
Added ref, math properties.
Fixed lots of minor little bugs.
Minor improvements to docs, VISA support and URL loader.
Merge branch 'dev' of github.com:cgranade/gpibusb-comm_code into dev
Added more documentation, Phase Matrix FSW-0020 support.
Fixed a few bugs with config file and URI functionality.
Merge pull request #8 from cgranade/dev

Pull in bug fixes and documentation improvements