Scalar redesigned

[amihaiemil]

fixes #200

• turned Scalar into an interface.
• BuiltPlainScalar for building YAML scalars
• ReadPlainScalarValue for reading Scalar values from a mapping or a sequence
• ReadPlainScalarKey for reading a plain Scalar key from a mapping.
• ReadFoldedBlockScalar and ReadLiteralBlockScalar

[coveralls]

Pull Request Test Coverage Report for Build 426

• 72 of 74 (97.3%) changed or added relevant lines in 15 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.7%) to 91.809%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/main/java/com/amihaiemil/eoyaml/AllYamlLines.java	0	2	0.0%

Files with Coverage Reduction	New Missed Lines	%
src/main/java/com/amihaiemil/eoyaml/AllYamlLines.java	2	69.23%

Totals
Change from base Build 414:	0.7%
Covered Lines:	863
Relevant Lines:	940

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💛 - Coveralls

[amihaiemil]

@rultor merge it

[rultor]

@rultor merge it

@amihaiemil OK, I'll try to merge now. You can check the progress of the merge here

[rultor]

@rultor merge it

@amihaiemil Done! FYI, the full log is here (took me 2min)