Remove makevalid algo

[coveralls]

Pull Request Test Coverage Report for Build 400

• 23 of 31 (74.19%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-2.2%) to 57.956%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
planar/makevalid/makevalid.go	7	10	70.0%
planar/makevalid/triangulate.go	16	21	76.19%
<!--	Total:	23	31	74.19%	-->

Files with Coverage Reduction	New Missed Lines	%
planar/makevalid/triangulate.go	1	65.91%
<!--	Total:	1		-->

Totals
Change from base Build 392:	-2.2%
Covered Lines:	18619
Relevant Lines:	32126

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💛 - Coveralls