dev: introduce FirstClassTheoremAttribute.
dev: imeplement CreateTestFixture.
dev: add FirstClassTheoremAttribute to the test

for generating nuget transform files.
dev: add tests to ensure the transform files have the 'Jwc.Experiment'

using directive.
dev: address some code-analysis warnings.
dev: add some scenario tests for FirstClassTheoremAttribute.
Merge pull request #32 from jwChung/first-class-theorem

FirstClassTheoremAttribute