Dynamic support for compression in high-level python api

Created by: isosc

Currently, using compression when writing with high-level python api requires a static XML file. This is awkward or impossible when this information is only available at runtime. As a workaround for simple cases, an xml file can be generated dynamically, but in general, not all xml content is necessarily known by the time of the first write call.

It would be helpful if compression could be added dynamically, perhaps as part of the write call.