Add Header.checkPow

[sethdusek]

For #767

[coveralls]

Pull Request Test Coverage Report for Build 13994202105

Details

• 37 of 43 (86.05%) changed or added relevant lines in 7 files are covered.
• 10 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.07%) to 78.402%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
ergo-chain-types/src/header.rs	5	6	83.33%
ergotree-interpreter/src/eval/sheader.rs	2	3	66.67%
ergotree-ir/src/types/sheader.rs	7	8	87.5%
ergo-chain-types/src/autolykos_pow_scheme.rs	20	23	86.96%

Files with Coverage Reduction	New Missed Lines	%
ergotree-ir/src/serialization/types.rs	10	78.77%

Totals
Change from base Build 13935643412:	0.07%
Covered Lines:	11257
Relevant Lines:	14358

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💛 - Coveralls