Move to Typescript

[StefanoMagrassi]

Description

Move to Typescript and drop support to Flow.
This issue is the first step to the v1.0.0 of the project and will be developed in the next branch of the repository (not published on npm).

Motivation

• full support to fp-ts-family libraries;
• better tooling;
• better development experience.

Steps

• prepare environment for Typescript
• rewrite typings using Typescript's syntax superseded by Implement a more functional API #12
• use tslint instead of eslint
• use Jest (with ts-jest) instead of AVA
• add Prettier and a precommit script in order to make code formatting consistent

[StefanoMagrassi]

resolved by #15