0.4.0

This release introduces a way to use container images as library packages, as described in RFC 0003.

It also includes some changes that make jk commands work more consistently:

• fileysytem writes are sandboxed similarly to filesystem reads PR 346
• jk transform and jk validate now read and write to the files given as arguments, even if they are given as absolute or parent paths (previously they were subject to the sandboxing, but this doesn't make sense for files that are named on the command line) PR 338
• there are now symbols in @jkcfg/std for stdin and stdout, to be used with read and write respectively PR 339
• jk validate and jk transform now handle YAML and JSON files containing more than one value PR 334
• jk generate will validate values if you include a validation function in its input, per RFC 0002