added fuzzy decoding for booleans, added ability to decode numeric keyed objects as arrays with fizzy decoder

[masterada]

rel https://github.com/json-iterator/go/issues/486

• decode the followings as boolean: "true", "false", 0, 1, "0", "1".
• allow unmarshalling numeric keyed objects with strictly increasing keys as array, eg: {"0": "a", "2": "b"}

The later is neccessary because of the "unset" php method, eg:

<?php

$a = ["a", "b", "c"];
echo json_encode($a); // prints ["a","b","c"]

unset($a[1]);
	
echo json_encode($a); // prints {"0":"a","2":"c"}

[masterada]

@taowen @AllenX2018 can some1 take a look at this please?

[pongraczgabor87]

@AllenX2018 Could you check this out? Would be nice to see these changes in one of the following releases.

[pongraczgabor87]

@taowen Would you have time to look into this?