Generic spectrum analyzer and DisplayXY modules, with 2 drivers and tests

[evgmik]

Hi,

This is quite large pull request.

• bug fixes in SCPI

  • lib/Lab/Moose/Instrument/SCPI/Display/Window.pm
  • lib/Lab/Moose/Instrument/SCPI/Sense/Power.pm
  • lib/Lab/Moose/Instrument/SCPI/Unit.pm

• 2 new roles

  • lib/Lab/Moose/Instrument/DisplayXY.pm intended for devices displaying XY traces, i.e. scopes and spectrum analyzers. It can display and log/save traces.
  • lib/Lab/Moose/Instrument/SpectrumAnalyzer.pm generic role for a spectrum analyzer

• Two drivers for spectrum analyzers using above roles

  • lib/Lab/Moose/Instrument/HP8596E.pm (updated to use new roles)
  • lib/Lab/Moose/Instrument/Rigol_DSA815.pm (new)

• There are test modules for above two drivers.

• No tests yet for DisplayXY