v0.8.1

Features:

1. Support for basic type definitions (e.g. aliases for base types)
2. Semantic Tag Namespaces & ZAP generation
3. ZAP errata now supports overriding cluster names and data type names, and excluding files and clusters from ZAP generation
4. Initial spec validation command for checking cross-references

Fixes:

1. Various data model lists are now sorted in a stable manner to prevent erroneous diffs
2. Command responses are now treated as full data types, and can thus use references to sections
3. Mode Tags are now included in ZAP generation, even when not directly referenced