WIP Blog Post: a la carte structural or nominal typing with derived corollaries

[andrew-johnson-4]

An "always fast-forward" derived corollary can be used to derive nominal types from structural types, or structural types from nominal types.

• implement corollary typing
• implement derived "Fields" type with corollary typing
• write a blog post explaining propositions and corollary typing and how it can be used to create higher-level type features
• mention performance benefits of nominal vs structural typing (a quick-prop can be inferred in constant time)

[andrew-johnson-4]

• always-fast-forward corollaries should be given their own lookup table:
• quick-prop: Hashtable<Tuple<String,U64>,List<Corollary>>