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fix `filter` overloads in `NonEmptyArray` / `ReadonlyNonEmptyArray`, c…

…loses gcanti#1388

version 2.9.3

version 2.9.2

sort / uniq: return the input when length <= 1, closes gcanti#1357

upgrade to latest gcanti/dtslint

Docs: more descriptions / examples in Option, Either

add "Derivable from" comments

version 2.8.4