dhall-lang/dhall-haskell

This is useful for integrating dhall to build systems where dhall
expressions (e.g. of type `Text`) are build products.

This also renames the `--list` flag to `--transitive-dependencies`

This commit adds a flag for producing a machine readable listing of
dependencies of a dhall expression.

This flag can be used to integrate dhall more easily to file watchers or
build systems which require such lists of dependencies.

Added `normalizeWith` function to complement `typeWith`.
Dhall is so very attractive base for simple DSLs that I felt it
needed to be pushed over the edge.

Naturally, using `normalizeWith` loses all the nice features of Dhall.
If your context isn't total or strongly normalizing then embedding it
to Dhall will not improve things.

This allows loading dhall 'modules' using a custom typing
context. See #83

Added a function that allows doing `input` from a closed
Dhall `Expr` instead of text. This is hugely useful when
working with Dhall in AST level (for example, using custom
types / normalization). For example, suppose that you have
built a custom primitive that requires a record as an argument.
With `rawInput` you can just extract the record into a Haskell
data type and process it without need to work with maps and other
bits of AST.

For context of this commit, see #79 (and also #26).