Description:
------------
JSON_NUMERIC_CHECK does not respect the definition of numbers.

I think will be great to add extra option like (JSON_NUMERIC_LEADZERO), to do not trailing zeros at the lead.

Extra reported as a bug many years ago: https://bugs.php.net/bug.php?id=70680

Test script:
---------------
print_r(json_encode(array("shouldBeString0123456" => "0123456", "shouldBeString+0123456" => "+0123456", "isInt" => "123456"), JSON_NUMERIC_CHECK | JSON_NUMERIC_LEADZERO));

Expected result:
----------------
{
    "shouldBeString0123456":"0123456",
    "shouldBeString+0123456":"+0123456",
    "isInt":123456
}

Actual result:
--------------
{
    "shouldBeString0123456":123456,    // Bad with JSON_NUMERIC_CHECK 
    "shouldBeString+0123456":123456,   // Bad with JSON_NUMERIC_CHECK 
    "isInt":123456                     // Good
}