Dhall for Java 0.3.2

This release fixes some minor Text parsing issues involving bracketed Unicode escapes (e.g. "\u{0020}") and indentation removal in multiline strings (trailing whitespace wasn't being properly taken into account). Please see the changes in #86 for details.

This release also moves the org.dhallj.ast package from dhall-scala into its own module (dhall-ast). The dhall-scala module depends on dhall-ast, so this move won't affect dhall-scala users. It does mean that dhall-testing no longer requires a dhall-scala dependency (only dhall-ast), so users of dhall-testing may need to add an explicit dhall-scala dependency. Because there are no binary-incompatible changes and only users of a testing dependency (may) need to change their build, I decided it would be reasonable to make this change in a patch release.