Fix failing test
Also emit xml from plain clojure maps
Make namespaced xml documents roundtrippable
Make it possible to emit xml-names qualified by uri with auto-prefixing
Add helper functions and macros for namespaced xml
- resolve-name: generate xml-names based on a namespace environment
- with-xmlns: write prefixed keywords to get xml-names in a lexical context
- walk-resolve-names: walk an xml tree and replace keywords with xml-names
- walk-cleanup-prefixes: remove redundant prefixes (multiple bound to same uri)