DITA-OT normalize plugin 2.0

What's Changed

• Use map-first preprocessing for normalization by @jelovirt in #15

Full Changelog: 1.1.0...2.0

DITA-OT normalize plugin 1.1

• Remove default, generated, and build-time attributes from output
• Rename file extension to common DITA extensions
• Remove key and branch filter artefacts

DITA-OT normalize plugin 1.0

DITA-OT normalize plugin 1.0