Support ReadSpeaker docReader

Absolutely @sunlix, I just wrote to them, and will share their reply here.

@sunlix: I got some info from ReadSpeaker support, about their ReadSpeaker docReader, please let me know if you need more details.

The primary way we think should be integrated into OpenReadSpeaker is the AutoAdd script. The script is loaded by adding the parameter revdload=DocReader.AutoAdd to the webReader.js script-url.

In addition, configuration is then done by this object:

window.rsConf.docReader

The most important are the language settings.
rsConf.docReader.lang: string with language to use for automatically added links
rsConf.docReader.hrefLang: boolean to indicate whether to use the hreflang of document links to determine language.

The configuration object looks like this:

window.rsConf = {
    docReader = {
        lang = "en_uk", // For example.
    }
}

The plugin should only create one rsConf object, and "merge" in the docReader member, as other keys control webReader itself.

If you want to supply a checkbox when uploading documents, disabling docReader for a specific link can be done by adding the class rspkr_dr_added.