Allow to use dynamically created translations

Currently, TimelineJS expects the language property to either

• be a string such as en indicating that some premade json file from a common path (defaulting to https://cdn.knightlab.com/libs/timeline3/latest/js/locale) should be used, or
• be a URL string ending with .json indicating that some particular premade json file should be used.

It is not possible, however, to use dynamically created language overrides, which would commonly be passed as a JSON object following the same structure as the translation JSON files.

A simple change to https://github.com/NUKnightLab/TimelineJS3/blob/master/src/js/language/Language.js#L242-L251 would allow this. If, for instance, the initial check at https://github.com/NUKnightLab/TimelineJS3/blob/master/src/js/language/Language.js#L243 was turned into

if (
  /\.json$/.test(code) ||
  /^blob:/.test(code) // dynamically created file (Data URL)
) {

then in particular 3rd party solutions that use TimelineJS as module could simply construct their own translation JSON object dynamically (let us call it foo) and pass it to TimelineJS as a Data URL, e.g. using

URL.createObjectURL(new Blob([JSON.stringify(foo)])) // in proper `try/catch`-clause, sure

If that's something that feels worth adding to TimelineJS (implementation can vary, of course), please let me know.

Start in src/js/language/Language.js around lines 242-251, where the language value is checked before loading a translation resource. Verify how a blob: URL is handled alongside existing JSON URLs, while preserving language-code behavior. Done means dynamically created translation JSON can be passed through a Data URL and used by TimelineJS.