1.22.0

• Add application/ppsp-tracker+json
• Add application/problem+json
• Add application/problem+xml
• Add application/vnd.hdt
• Add application/vnd.ms-printschematicket+xml
• Add model/vnd.rosette.annotated-data-model
• Add text/slim
• Add extension .rng to application/xml
• Fix extension of application/dash+xml to be .mpd
• Update primary extension to .m4a for audio/mp4