Improve mappingToCSV

[stefandesu]

• [x] Return object with multiple functions instead of a single function (see below).
• [x] Add support for compound mappings.
• [x] Add function to get header.
• [x] Add support for multiple mappings which also includes the column headers.

let csv = jskos.mappingCSV({
  lineTerminator: "\r\n"
})
// single mapping
csv.fromMapping(mapping)
// multiple mappings (includes header by default)
csv.fromMappings(mappings, { header: true } )
// get header based on list of mappings (also used by "fromMappings")
csv.header(mappings)

This is needed for https://github.com/gbv/cocoda/issues/185.

[stefandesu]

• [x] Include fromScheme/toScheme with an option

_{Sent with GitHawk}

[stefandesu]

Bump. Related to https://github.com/gbv/cocoda/issues/185.

[stefandesu]

@nichtich How should compound mappings look like in the exported CSV?

[nichtich]

As suggested at https://github.com/gbv/cocoda/issues/185#issue-373449654: add columns such as toNotation2, toNotation3..

[stefandesu]

I missed that, thanks!

[stefandesu]

Opened a PR: https://github.com/gbv/jskos-tools/pull/20

[stefandesu]

Merged.