added url(translator) support for <paragraph>

[coderofsalvation]

Ok, honestly this is something I'm pretty excited about:

as discussed earlier, this adds (cached) url-support for <paragraph> via translators:

video-10.mp4

click here for the JML-source of video

First I had hardcoded HTML-urlsupport only..
But then I realized we might want to introduce the beloved 'translator'-concept here as well..
This maximizes the potential of pulling in content from various ecosystems/protocols.
Her's a demo of an custom translator: https://codeberg.org/coderofsalvation/janus-script-activitypub

<paragraph> comes with a default (XML) translator, so janusweb can handle RSS/XML/HTML urls out of the box.
It can also even translate itself! (room.fullsource)

The source-header explains all the possibilities:

 * <paragraph> text-to-texture translator. The builtin XMLtranslator allows:                                                                            
 *                                                
 *  1. inline html             : <paragraph><![CDATA[ <b>hello world</b> ]]></paragraph>
 *  2. inline html (partial)   : <paragraph selector="span"><![CDATA[ <b>hello <span>world</span></b> ]]></paragraph>
 *  3. external url            : <paragraph url="https://janusxr.org"/>
 *  4. external url (partials) : <paragraph url="https://janusxr.org" selector=".infoText"/>
 *  5. janusroom container html: <paragraph selector=".someclass"/>
 *  6. janusroom container xml : <paragraph selector="tag subtag title"/>
 *  7. RSS                     : <paragraph url="https://my.org/foo.rss" selector="item description"/>
 *  8. XML                     : <paragraph url="https://my.org/bar.xml" selector="title"/>
 *  9. any data- or selector-format via 'paragraph_translator' event                             
 *                                                                                                
 *  NOTES:                               
 *  1. By default, selectors are done via `document.querySelectorAll`
 *  2. in case of multiple results:                   
 *    2.1 clicking the paragraph with cycle through them
 *    2.2 setting cycle="2000" allows for (2sec per item) slideshows                       
 *    2.3 setting `rooms.objects.myparagraph.index++` cycles to next item
 *  3. width/height-attributes offers finer control of texture size
 *  4. ttl-attributes allows finer control of webrequest-cache (default 2 mins)
 *  5. setting `rooms.object.myparagraph.selector = "#section2"' allows for statemanagement  

custom translators

Whenever a <paragraph> fetch/renders itself, the room will emit an paragraph_translator event, with (a copy) of the default translator

room.addEventListener("paragraph_translator", function(e){
  const {translator,paragraph} = e.detail
  // now you can override the default translator
  translator.fetch       = async (url) => this.text = "a response"  // my custom fetch function
  translator.translate = () => this.html = this.text                // my x2html translator
}