Make custom template and locale functioning easier

[larsgw]

The current way of using custom templates and locales is confusing to say the best (see #28). Expected features:

• default and custom template and locale registers, with appropriate methods
• way to amend templates

[larsgw]

I outlined some possible APIs in a recent blogpost:

const template = '...'
const templateName = 'custom'

// Suggested new API
Cite.CSL.template.register(templateName, template)

// Nothing new, will stay the same
const data = new Cite(...)
data.get({
  type: 'html',
  style: 'citation-' + templateName
})

// prepends the id like this: "[$ID]: "
const prepend = ({id}) => `[${id}]: `
// appends an altmetric widget
const append = ({DOI}) => `<span class='altmetric-embed' data-doi='${DOI}'></span>`

// Nothing new, will stay the same
const data = new Cite(...)
data.get({
  type: 'html',
  style: 'citation-' + templateName,
  // Suggested new API
  // both properties either function or constant string
  append: append,
  prepend: prepend
})

---

I'm currently working on the implementation, and it will be slightly different, but not structurally (probably only method names):

const template = '...'
const templateName = 'custom'

// Suggested new API
Cite.CSL.register.addTemplate(templateName, template)

// Nothing new, will stay the same
const data = new Cite(...)
data.get({
  type: 'html',
  style: 'citation-' + templateName
})

[larsgw]

I failed to mention this here earlier, but the first part of the API change happened in 3aaaf7c (or v0.3.0-11). For current API, see here for templates and here for locales. Ping @austinjp.

[austinjp]

Great work @larsgw , really appreciate it. I'll have a detailed look another day!