Export of database from .h5 to .h5 on Linux is buggy

[eneelo]

Describe the bug
On Linux, h5-file exported on Linux is corrupted when database is imported from .h5

To Reproduce
Steps to reproduce the behavior:

1. Import .h5 file produced by SIMA to qats.TsDB
2. Export database to new .h5 file.
3. Import .h5 file exported above.
4. Try to extract one or more time series from the database. This will produce an error like "KeyError: 'Unable to open object (component not found)'" (error message possibly depends on whether the new .h5 file is imported on Linux or in Windows).

Expected behavior
The recipe above should not produce an error.

Screenshots
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Desktop (please complete the following information):
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Additional context
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[eneelo]

Inconsistencies found in qats during debugging so far:

• qats.io.sima_h5.read_names() inserts a backslash ('\') as separator between datagroups and between datagroup and dataset.
• qats.tsdb.TsDB._make_export_friendly_names() replaces the OS depedendent separator (which is '/' on Linux) by an underscore ('_'), meaning that the backslash inserted by sima_h5.read_names() is not replaced by an underscore.

It is unclear whether this is what causes the bug or if there are additional issues. Suggested steps to fix/identify the issue:

• Fix inconsistency described above (e.g., by using system separator to separate datagroups/-sets at import).
• Test import/export/import on Linux. If this doesn't fix the problem, further debugging is required.
• Consider adding a import/export/import of .h5 as a unit test.