Add support and tests for relcast

[vihu]

No description provided.

[coveralls]

Pull Request Test Coverage Report for Build 282

• 12 of 20 (60.0%) changed or added relevant lines in 5 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.06%) to 84.828%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/hbbft.erl	3	5	60.0%
src/hbbft_cc.erl	1	3	33.33%
src/hbbft_rbc.erl	4	8	50.0%

Files with Coverage Reduction	New Missed Lines	%
src/hbbft_acs.erl	1	93.24%

Totals
Change from base Build 275:	-0.06%
Covered Lines:	369
Relevant Lines:	435

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💛 - Coveralls