Decode unions the same way as_dhall makes them
Use Dhall names for everything that encodes untagged
Disambiguate hoisted union tags properly

An array may contain two nomnatively-equivalent types who are
structurally different -- so they need different (but related) union
tags since they will not share a type.
Enum should not have itself in the alts
More useful to_s for AST nodes
Normalize list element types before comparing
Facility to flatten let blocks
Prefer double quotes for strings
Update and run latest alpha-normalization tests
Initial dhall-compile script

Add to build that after tests pass we compile the whole Prelude
Fix for stack level too deep on long comment
Allow typechecking filled builtins
Add new useful facilities to Function
as_dhall for Proc

Cannot actually serialize this, but can be useful for passing functions
in to Dhall functions, etc.
Update to latest dhall-lang
Handle self-describe tag anywhere
Fix for substitute on LetBlock/LetIn
Improve the multiline algorithm

Require that the whitespace being stripped is a common prefix.
Allow tabs and blank lines in multiline strings
Hoist single-label enum into array