missing information when saving to version 4 with noDataLoading=True

[danielhrisca]

Some important information is missing from the channels when saving to mdf version 4 noDataLoading=True:

• channel unit
• channel min/max values
• channel comment

For example the signal _MAINCLOCK from the test file:

and the saved file has:

[danielhrisca]

with the latest commit the information are missing for all mdf options (nodataloading, compression, default)

[ratal]

Yes, I also noticed a regression there, investigating

[danielhrisca]

fixed