Update to latest dhall-lang
Fix for substitute on LetBlock/LetIn
Hoist single-label enum into array
Remove empty re-opens from normalize
Normalize text concat as interpolation
Add grab-bag of useful utils onto expressions
Run all dhall-lang tests for normalization
Update to new UnionType selection semantics
Fix rubocop except for parser metrics
fix type => [value|element]_type
Refactor LetBlock, allow single LetIn
Clean up style violations
Remove multi-argument applications
They only exist in binary encoding, so let's keep them there.
Make every Expression a ValueSemantics and use the known list of
attributes to map generically over any AST node.
Introduces a conditional, but removes boilerplate from every single
Internal flag to disable for acceptance tests from the standard (which
assume beta-only normalization in some cases). Otherwise, just always
alpha normalize as we go.