Error in assignment to multidimensional arrays

There's a problem with [] (indexing) operator. Indexing with with one number can be used to read value from the entire table, but it cannot be used to write to multidimensional table. While indexing with 2 or more numbers you can write to any table.
I am not sure, if it is the consequence of C implementation or problem with the wrapper, but this behavior is very unintuitive.

Checked on CPU and OpenCL Backend.
I'll try to fix it on my own
There's an example of the problem

```
ArrayFire.Array A1D = Data.CreateArray(new int[] { 1, 2, 4 });
A1D[1] = Data.CreateArray(new int[] { 100 });
Util.Print(A1D, "A1");

A2D[0, 0] = Data.CreateArray(new int[] { 11 });
A2D[1] = Data.CreateArray(new int[] { 100 });
Util.Print(A2D, "A");

A3D[1,1,1] = Data.CreateArray(new int[] { 100 });
A3D[0, 1] = Data.CreateArray(new int[] { 100 });
A3D[0] = Data.CreateArray(new int[] { 100 });
Util.Print(A3D[1,1], "A3D");
```
Generates the output

```
A1D
[3 1 1 1]
1
100
4

A2D
[3 3 1 1]
100 -1 4
2 2 2
4 0 3

A3D
[2 2 2 1]
1 100
2 -1

2 4
0 100
```

Start at the [] indexing and assignment entry points in the .NET wrapper, then reproduce the supplied A1D, A2D, and A3D examples on both CPU and OpenCL backends. Trace whether single-index writes to multidimensional arrays are handled by the wrapper or ArrayFire implementation; done means the documented assignment cases behave consistently across both backends.

Written by the indexing model from the issue text.