Add support for optional strict validation of types

[adi69]

One should have the freedom to check for types inside strings.
For instance, given the following schema

    {
        "schema": {
            "id": "schema_id",
            "properties": {
                "age": {
                    "type": "integer",
                    "description": "",
                }
            }
        }
    }

above schema should validate true for following data when strict validation is False

{ "age": "23" }

Why? It'll be helpful in API validation of query in GET requests and headers.

[Julian]

This sounds like the opposite of "strict" :)

It's possible already though to do now that we've got fully extendable type checkers. Haven't tidied up enough to do a release just yet, but if you give HEAD a try you'd be able to do this.

Feedback welcome.