WIP: enable zst compression using new compress= kwarg
FIXME: The one-liner expression that many scripts have to pass to
`write_filename` will become unwieldy as the number of available
compression methods grows from 1 to 2 or even more. Instead of this:
```python
write_filename(
filename,
compress = compress = 'gz' if (options.output or "stdout").endswith(".gz") else False
)
```
this patch proposes a new `compress_for_filename` helper function:
```python
write_filename(
filename,
compress = compress_for_filename(filename)
)
```
However, even this breaks the DRY principle.