Changes
===========================
Between Lab::Instrument, Lab::Tools, and the initial release of Lab::Measurement
(Summary of the most important points only)
Lab::Measurement
* The default file suffixes have been changed from "DATA" and "META" to "dat"
and "meta".
Lab::Instrument
* The back-end has been completely restructured, introducing the classes
Lab::Connection and Lab::Bus.
* SR830: functions like get_range and get_tc do not return strings anymore,
but values in SI base units