Bloody footprints never dry

[Lady Birb]

Normal, plain old blood pools will eventually dry, but bloody footprints will always be considered wet. This causes two problems: The footprints are always slippery, and the blood can get on your shoes, resulting in more footprints, resulting in more slippery tiles until a single papercut results in all of medbay, the cafeteria, and escape being impossible to pass without slipping at least once.

Also I noticed that dried blood, while not slippery, can still cause you to leave footprints, resulting in slippery tiles. Fix this too.