Also first tests for cJSON_Minify.
Thanks @bigric3 for reporting

Thanks  @raiden00pl for reporting

Thanks @AlfieDeng for reporting

If the `string` property of the item that is added is an alias to the
`string` parameter of `add_item_to_object`, and `constant` is false,
`cJSON_strdup` would access the string after it has been freed.

Thanks @hhallen for reporting this in #248.

Thanks @liuyunbin for reporting this in #230

Thanks @liuyunbin for reporting this in #230

Thanks @liuyunbin for reporting this in #230

These functions return the added object. Functions to add objects and
arrays have also been added.

A macro named `ENABLE_LOCALES` was added and an option with the same name too in the CMakeLists.txt

pointer in error case and change code to match new expectations.