Reactivate metadata view

[bwbohl]

Description, Context and related Issue

reactivate metadata view

closes #361

How Has This Been Tested?

BAZ-GA internal edition klarinettenquintett

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [x] reactivation of previous feature

Checklist

• [x] I have performed a self-review of my code
• [x] I have read the CONTRIBUTING document.

Additional steps

• [x] get MetadataView working for MEI files
• [x] get MetadataView working for TEI files
• [ ] improve MEI output
• [x] improve TEI output
• [ ] improve styling