v0.7.6

• add Either.filter
• optimize Option.sequence & Either.sequence
• add Option.traverse & Either.traverse
• add support for Futures (Promise wrapper)
• take advantage of conditional types for a more precise type for partition, see http://emmanueltouzery.github.io/blog/posts/2018-04-07-prelude-type-guards.html

With this release, prelude.ts now requires typescript 2.8.3 or newer (or plain javascript of course).