Maps do not allow tagged values as keys

[Former user]

Tagged values are perfectly acceptable as keys in EDN:

user=> {(java.util.Date.) 'test}
{#inst "2018-11-23T17:51:11.759-00:00" test}

but hedn fails to parse any Maps with tagged values:

> decode "{#inst \"2018-11-23T17:51:11.759-00:00\" test}" :: Maybe Value
Nothing
> decode "[#inst \"2018-11-23T17:51:11.759-00:00\" test]" :: Maybe Value
Just (Vec [Tagged (String "2018-11-23T17:51:11.759-00:00") "" "inst",NoTag (Symbol "" "test")])

The definition of EDNMap appears to be more restrictive than necessary, only allowing untagged keys:

type EDNMap = Map Value TaggedValue

According to the spec:

A map is a collection of associations between keys and values ... Note that keys and values can be elements of any type.

So it should be OK to change this to type EDNMap = Map TaggedValue TaggedValue

[dp wiz]

Thanks! The restriction is lifted in a new version in #6.