Wrong namespaces used in DWA Compressor.

[JuriAbramov]

Default value are used instead of aliases.
Please pull requests #131 (#131).

I'd appreciate if it would go into v2.2.1.

[cary-ilm]

Looking into the OpenEXR issue backlog. This appears to have been resolved in v2.3.0 but never closed. Closing now.