Changelog for futhask

Unreleased changes

Change in the name of the Monad from FT to Fut. This is a breaking change, but in principle a simple search and replace should fix it. The motivation for the change is both that it is more descriptive, and the introduction of the transformer. FutT simply looks better then FTT, especially in names using CamelCase. The original name FT was inspired by ST, since they both use rigid type variables for similar purposes.