improve internal `mergeAll` function, closes gcanti#532

Experimental: make `sum` safer, closes gcanti#523

version 2.2.11

version 2.2.10

add `Wrap` member to DecodeError + add `withMessage` combinator to `D…

…ecoder` and `TaskDecoder`

update changelog

make JsonRecord readonly

`intersection` should accumulate all errors

fix type information lost from nested decoder types, closes gcanti#479

remove the dependency on the `either` instance as a mean of improving…

… tree shaking