Strange surface plot

Hi, on my machine, the surface plot seems to have multiple issues. If I run the following code:
```c++
#include
int main(int argc, char *argv[])
{
try {
af::info();
af::array X = af::seq(0., 0.4, 0.1);
af::array Y = af::seq(0., 0.9, 0.1);
af::array Z = af::constant(1., 5, 10);
af::Window window(1500, 800, "The door.");
do {
window.surface(X, Y, Z, "The weird surface");
} while(!window.close());
} catch (af::exception& e) {
fprintf(stderr, "%s\n", e.what());
throw;
}
return 0;
}
```

I see the following image (without the red lines):

The image has a few problems:

1. The Y-axis labels are all the same.
2. The X-axis labels are probably all the same as well.
3. The surface is plotted in wrong position and probably scaled badly (hard to say).

System version:
```
ArrayFire v3.6.0 (OpenCL, 64-bit Linux, build default)
[0] INTEL: Intel(R) Core(TM) i7-7500U CPU @ 2.70GHz, 15930 MB
Linux pine 4.13.11-1-ARCH #1 SMP PREEMPT Thu Nov 2 10:25:56 CET 2017 x86_64 GNU/Linux
Both Forge from devel branch and from arrayfire behave the same, CPU backend as well.
```

Also when I resize the window, the program crashes with:
```
Failed to blit
[1] 788 segmentation fault (core dumped) ./a.out
```
Thank you for your help and for a nice high-performance visualization tool!