Speedups for making ARGB arrays for Qt

I made some tweaks that allow single channel images to be created 200% faster and color images 30% faster.  The trick I used is to make the array contiguous to start, so nothing has to be done in `makeQImage`.

```
argb, alpha = makeARGB(image, transpose=True) 
return makeQImage(argb, alpha, transpose=False, copy=False)
```