coverage: count number of executions per line #1986

Job	Run time
Build Echidna on ubuntu-20.04	5m 34s
Build Echidna on macos-13	5m 57s
Build Echidna on windows-latest	13m 58s
Test with solc 0.4.25 on ubuntu-latest	4m 45s
Test with solc 0.5.7 on ubuntu-latest	3m 32s
Test with solc 0.6.12 on ubuntu-latest	4m 10s
Test with solc 0.7.5 on ubuntu-latest	4m 18s
Test with solc 0.4.25 on windows-latest	4m 18s
Test with solc 0.5.7 on windows-latest	4m 17s
Test with solc 0.6.12 on windows-latest	4m 41s
Test with solc 0.7.5 on windows-latest	6m 25s
	1h 1m 55s

Provide feedback