Quantized height width window improvements

Love your work eczarny - this makes OSX much more usable.

Evolution of #209

**Problem**

As a dev I do spend a lot of time in quantized size windows e.g. Terminal

The left/right and thirds functions have never really worked properly for quantized size windows, relying on the fudge factor.

Also, quantized size windows were not centred nicely after they were relocated.

**Solution**

Use more intelligent window containment/centre locations to detect current position, allowing it to get it right for quantized size windows.

When the window doesn't move exactly into the location we want, iteratively reduce the size until it fits, then centre it in our desired location.

**Notes**

I did remove the artificial 1px gap introduced between half windows.

**Testing**

* 10.9.4
* Multi monitor, non retina
* Retina
* With and without "displays have separate spaces"
* Dock autohiding
* Dock on every side

**Release**

Please delay release of this: I have a further PR, to get around moving docks on multiple monitors.

I'd like both out in the same release, however I'd prefer we got this one merged into master before submitting that one.