chat-procs overhaul:
- don't double encode everything
- avoid deprecated js functions escape()/unescape()
xowiki/www/ajax/streaming-chat.js, xowiki/www/ajax/scripted-streaming-chat.js
- scripted-mode: fix incorrect markup
- fix parameter passing to xowiki/www/ajax/chat.tcl to avoid rejects
- fix json_encode: one quote to man in xotcl-core/tcl/chat-procs.tcl
- don't dropt "user has_entered_the_room" in "xo::Chat instproc login",
since xowiki chat has otherwise no idea, who is logged in