Idea: Create MurmurHash comparison strategy

[lukasz-pekala]

This seems to be quicker (still probably slower than counting pixels :) ) than MD5 and widely adopted (e.g. Elasticsearch):
https://stackoverflow.com/questions/3665247/fastest-hash-for-non-cryptographic-uses

New projects could use it. For existing projects this would require 'marking as pattern' or some kind of a migration tool.
We can now implement strategies side-by-side with HashComparisonStrategy (this would need to be renamed to MD5HashComparisonStrategy) and PixelByPixelComparisonStrategy

[lukasz-pekala]

Seems there's even something faster:
https://github.com/Cyan4973/xxHash
https://github.com/noricube/xxHashSharp (not updated project though...)

[lukasz-pekala]

Counting pixels turned out to be the fastest. Hashes are not needed for our tests