load/save samples

[heeplr]

Is your feature request related to a problem? Please describe.
Inspecting signals is quite nice, but there is no way to inspect past signals. It's already possible to export to csv but no way to import.

Describe the solution you'd like
Menu options:

• File -> Save - will save the current buffer to a file.
• File -> Load - will load a buffer from a file and adjust the settings accordingly (samplerate etc.)

Describe alternatives you've considered
An alternative would be an "Import CSV" option but I think there's no need for the ASCII conversion.

Additional context
Thanks a lot for your work on OpenHantek6022!

[zen67]

I can test it.