lforms-loader

This is a package for loading LHC-Forms (lforms) into a webpage by adding the needed link
and script tags to the page.

Exported functions:

* loadLForms(version, styleCallback, lhcFormsSource): This adds tags to the
current page to load LHC-Forms, and returns a promise that resolves when the
files have been loaded (or fail to load, in which case the promise will be
rejected).
* version: the version to be loaded (e.g., '33.4.1').
* styleCallback: (optional) a function to call as soon as the lforms styles are loaded
* lhcFormsSource: (optional) a base URL from which the lforms files can be
retrieved. If not specified, the NLM lhcforms-static website will be
used as the source.

* getSupportedLFormsVersions(): Returns a promise that resolves to an array of
the available lforms version strings for the versions supported by this loader
script. The versions will be sorted, with the most recent version first.

* changeLFormsVersion(newLFormsVersion): Handles a selection of a new LForms
version by reloading the page to the same URL but with the parameters "lfv"
set to the new LForms version. The app should then call the loadLForms
function to load that requested version.
* newLFormsVersion: the new version to switch to (assumed valid)

* loadLatestLForms(): Loads latest released version of LForms. If it fails, it
attempts to load the previous version. It uses getSupportedLFormsVersion() to fetch
the latest and previous versions and attempts to load the latest first. If that
version cannot be loaded, it attempts to load the previous version. If it succeeds,
the returned promise resolves to the loaded version.