Add option to resize captured image before comparing

[reboot]

Is your feature request related to a problem? Please describe

I tried to use AutoSplit with OBS Virtual Camera, because it allows me to use a single source from OBS for splitting without having to worry that something is wrong in the OBS window. Unfortunately the OBS Virtual Camera always uses the same resolution as the OBS output size. For a 1080p stream/recording you cannot change it. Comparing a high resolution image causes a lot of CPU load by AutoSplit. To detect a split image it is often not needed to compare it with the full resolution image. I tried setting OBS to a low resolution and it worked fine, but you can not stream/record like this.

Describe the solution you'd like

Add an option to scale an image to a lower resolution before it is compared with a auto split images. This should probably cause much less CPU load than comparing it to an auto split image at full resolution.

[Avasam]

AutoSplit already resizes all images to a common size for consistency in comparison. And we already do so to a pretty small 320x240 for performance reasons (without absolutely destroying accuracy).

AutoSplit/src/AutoSplitImage.py

Lines 33 to 37 in a4eaf27

	# Resize to these width and height so that FPS performance increases
	COMPARISON_RESIZE_WIDTH = 320
	COMPARISON_RESIZE_HEIGHT = 240
	COMPARISON_RESIZE = (COMPARISON_RESIZE_WIDTH, COMPARISON_RESIZE_HEIGHT)
	COMPARISON_RESIZE_AREA = COMPARISON_RESIZE_WIDTH * COMPARISON_RESIZE_HEIGHT

A similar feature request that would help if using masks is auto-cropping (#159) .
I've also been thinking that allowing custom resizes could:

1. help preserve more accuracy when cropping down to very small images using masks
2. Allow more accuracy when on more powerful hardware.

I've also had a few attempts at #219 but they all ended up with worst performance overall.