Typescript Optional Versions Save

No changes from the pre-release (2.0.1-alpha).

[email protected] has been abandoned because of a problem.

• Fixed problem about deployment.
• Fixed README.

Because this release contain breaking changes against the last release (v1.8.0), the major version has been changed to 2 from 1.

Features / Interface

• Added method Optional.toJSON for JSON.stringify. (breaking change)
• Optional#map now represents that it exactly returns a value whose payload is non-null type. (breaking change)
• Optional#isPresent and Optional#isEmpty are now method instead of accessor to adapt to the style of Java's isPresent. (breaking change)
• The supported version of TypeScript is now 3 from 2. (breaking change)
• Optional is now exported as non-default. (breaking change)

Changes for Development

• Changed directory structure of test.
• Changed directory structure exported to node_modules.
• Abandoned using istanbul directly and introduce nyc and ts-node for testing and coverage.
• Introduced TSLint.
• Publish for npm is performed automatically from Travis CI.

Features

• introduce Option<T> type.
• add method Optional.from.
• add method Optional.toOption.
• add method Optional.orNull.
• add method Optional.orUndefined.
• add method Optional.matches.

Improvements

• fix descriptions of tests.
• fix JSDoc document.
• replace keyword let with const for constants in effect.
• add to README.

Improvements

• support JSDoc document for all methods.
• fix descriptions of tests.

Improvements

• fix descriptions of tests.
• make tests more strictly using assert.strictEqual instead of assert.equal.
• replace keyword let with const for constants in effect.