unravel_index() argument name dims is not consistent with other functions

[SnoopJ]

The unravel_index() function takes an argument named dims that corresponds to:

The shape of the array to use for unraveling indices.

It seems like in most other places, this argument would be named shape, so I propose to rename it to match that convention, unless there is some special reason for this name to be different.

[eric-wieser]

I agree that shape is a better name, but we need to not break code that calls np.unravel_index(inds, dims=(...,)). The easiest way to do that in the C code is something like:

// pseudocode
if (ParseNewArgs(...) < 0) {
    save_current_exception();
    if (ParseOldArgs(...) < 0) {
        restore_exception();
        return NULL;
    }
    print_warning_about_old_argname();
}

Edit: This is a bad idea as it produces misleading error messages