concat segments

This kind of segment stores all data in a single file, simply concatenated one after the other.

It is suitable for formats whose workflow naturally concatenates data, such as GRIB or BUFR.

The file name represents the period of time stored in the segment. The file extension represents the format of the data it contains.

Optional padding

For VM2 data, which is a line-based format, the segment supports padding data with a newline. The newline is not considered part of the data, and it still gets written, skipped on read, and not considered as a gap during checks.