Add data when multiple dimensions (each sensor one dimension)

[tillmrtz]

I the newer datasets each instrument on the glider creates its own dimension. It appears that the majority of the associated data is also stored under the respective dimension, see image:

This is not taken into account during the conversion process, meaning that all data not stored under the main variable (sg_data_point or now sometimes ctd_data_point) is lost.
I will investigate this further, but it seems that the code needs to be adapted depending on whether all data is stored under the main dimension or whether the data for each instrument should be interpolated using the respective timestamp.