Shape detection is too unreliable

[vocksel]

Currently, shapes are not recognized as well as they should be, as pointed out by many uses on Twitter.

https://twitter.com/kevin1themorgan/status/1369436721968996364
https://twitter.com/ayameart/status/1369643717334859779
https://twitter.com/EugenicsOdyssey/status/1369595972037320706

I think this will mostly require tightening up the ratios we use, and limiting them to a specific range. If we are not within a range of certainty for a shape, it should be discarded completely. Worse case, we should return nil when we have no idea what shape the user drew.

[vocksel]

Coming back to this, the problems I notice most with shape detection is that:

• Circles get interpreted as squares a lot
• Squares/rectangles are too precise
• Chevron detection is too loose. You can essentially draw a half-circle and Geo thinks it is a chevron.

If we can tighten up these areas, shape detection should be a lot more reliable