Fixed "null window found" message on Windows

Previously no program name was defined in the Windows version. This didn't break anything, but it did cause the word 'null' to appear in lots of the log messages. I've now set the program name to 'Hearthstone', which is a much better name for a game than 'null'
Filtered out invalid ranks

If the OCR detects an invalid rank (ie higher than 25) then it will now ignore it instead of assuming you're actually bad enough to be ranked 116.
Much more accurate rank detection

Changed the way the screenshot of the rank is filtered so that only the number is extracted and all background is completely removed. This results in an almost perfect image for OCR, so the rank detection is extremely accurate now.

As a bonus the new filtering method is way faster than the old one, at least ten times faster!