Change dhall type to resolve imports (#1281)

* Change `dhall type` to resolve imports

Fixes #1277

The original motivation was that `dhall type` would represent a
type-inference-only phase.  However, in practice that wasn't very useful
so `dhall type` now performs import resolution followed by type inference.

* Fix loading relative to root directory

... as caught by @sjakobi

Co-Authored-By: Simon Jakobi <[email protected]>

Author: 2 people

dhall/src/Dhall/Main.hs

@@ -460,7 +460,7 @@ command (Options {..}) = do
         Type {..} -> do
             expression <- getExpression file
 
-            resolvedExpression <- Dhall.Import.assertNoImports expression
+            resolvedExpression <- Dhall.Import.loadRelativeTo (rootDirectory file) expression
 
             inferredType <- Dhall.Core.throws (Dhall.TypeCheck.typeOf resolvedExpression)