Intronix Logicport LA1034 input file format support

libsigrok now supports a new input format, the native file format used by the Intronix Logicport LA1034 logic analyzer.

These "LogicPort File" (*.lpf) files are created by the Intronix LogicPort Windows-only vendor software and you can now import them into sigrok frontends, e.g. sigrok-cli or PulseView:

  $ sigrok-cli -i foo.lpf -I logicport [...]

The code was contributed by Gerhard Sittig, thanks a lot!