The behavior of the json_object_array_put_idx() is that, if a user wants to
insert an element inside a JSON array, the element will be replaced.

For some cases, a user would want to insert an element into the JSON array
and shift the elements to the right.

For indexes that are outside the length of the current array this behaves
like json_object_array_put_idx().
If a user wants to enforce that the JSON array is not expanded, then the
json_object_array_length() function can be used to guard against that.

The main driver for this change is JSON patch, where the 'add' operation in
an array means inserting a value at a certain index and shifting everything
by one.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

See also issue #658.

Also add the json_object_new_array_ext, array_list_new2, and array_list_shrink functions.

Keeping this would be inconsistent with the other documentation

I also added a couple trivial, but related, suggestions.

closes #460

Fix json_object_object_foreach to avoid uninitialized variable warnings
using ANSI C or MSC.

In VS 2015, the warning text is "warning C4550: expression evaluates to a function which is missing an argument list".

Because doing `json_tokener_parse(json_object_get_string(src))`
feels sloppy, dirty, and makes me want to cry at night
sometimes.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

Issue #338, add json_object_add_int functions

Windows: Fix dynamic library build with Visual Studio