Speed up __eq__

[Tinche]

Create the __eq__ as a chain of ANDed comparisons, instead of a tuple.

On my computer, a class with two attributes now compares almost twice as fast: 141 ns vs 222 ns.

This will introduce a very slight incompatibility which I think is worth it for us (and dataclasses already introduced): attributes that compare equal by identity but not by value (= NaNs) will behave differently.

[codspeed-hq]

CodSpeed Performance Report

Merging #1310 will improve performances by 63.24%

_{Comparing tin/faster-eq (828e055) with main (feb7a4d)}

Summary

⚡ 2 improvements
✅ 6 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	tin/faster-eq	Change
⚡	test_eq_equal	1,136.4 µs	873.3 µs	+30.12%
⚡	test_eq_unequal	1,098.1 µs	672.7 µs	+63.24%

[hynek]

cool thanks! 🏎️