Pygeometa

- OARec: safeguard `time`, `properties.created`, `properties.updated`

- MCF core: make identification topiccategory, fees, accessconstraints, maintenancefrequency optional (242)
- OARec: write keywords as theme/concepts if vocabulary exists (233)
- OARec: safeguard properties.rights
- WMO WCMP2: various fixes based on specification updates
- CLI: add -o as short option for --output
- ISO: distribution: ensure format_version exists or emit gco:nilReason=missing (240)

- OARec: bug fixes for keywords and null time intervals

- OARec: fix ref

- OARec: emit default keywords as bare keywords, not themes/concepts
- OARec: fix roles, updates based on latest draft
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- fixes to MCF reference documentation

- add support for detailed schema information (223)
- add thesaurus handling to ISO import(226)