WebXDC improvements

* WebXDC "store" to choose a widget to add
* WebXDC UX improvements, especially for widgets that use touch events
* WebXDC experimental "realtime" API support
* Improve display of images shared from WebXDC
* Fix top spacing in chat bubbles
* Fix colour of "send private message" indicator
* Improve thread identicon contrast
* Fixes for rich reply markup processing
* Fix for large font on a retracted message that was a reply
* Improvements to showing what a MUC "actually" sent
-----BEGIN PGP SIGNATURE-----
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=l6Tb
-----END PGP SIGNATURE-----