Transparent background + fix

* Builtin Prosody, Share chat url: option to have a transparent background (for streaming integration).
* Builtin Prosody, Share chat url: fixed new day hidding when no scrollbar in readonly mode.

conversejs/index.html

@@ -24,7 +24,8 @@
     advancedControls: '{{ADVANCEDCONTROLS}}' === 'true',
     autoViewerMode: '{{AUTOVIEWERMODE}}' === 'true',
     theme: '{{CONVERSEJS_THEME}}',
-    forceReadonly: '{{FORCEREADONLY}}' === 'noscroll' ? '{{FORCEREADONLY}}' : '{{FORCEREADONLY}}' === 'true'
+    forceReadonly: '{{FORCEREADONLY}}' === 'noscroll' ? '{{FORCEREADONLY}}' : '{{FORCEREADONLY}}' === 'true',
+    transparent: '{{TRANSPARENT}}' === 'true'
   })
 </script>
 </body>