Partition and ExtendableSquareMatrix data structures #439

Job	Run time
run-test-performance-base (ubuntu-latest)	2m 57s
run-test-performance (ubuntu-latest)	2m 58s
run-test-performance-base (macos-latest)	2m 27s
run-test-performance (macos-latest)	2m 34s
run-tests (ubuntu-latest)	2m 28s
warnings-base (ubuntu-latest)	2m 36s
run-tests (macos-latest)	4m 35s
warnings-new (ubuntu-latest)	1m 57s
warnings-base (macos-latest)	1m 54s
warnings-new (macos-latest)	2m 51s
compare-versions (ubuntu-latest)	8s
compare-versions (macos-latest)	11s
compare-performance (ubuntu-latest)	28s
compare-performance (macos-latest)	31s
code-coverage	1m 56s
	30m 31s

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