OO-622,CL-225: remove username from GUI in place where is not really needed and students can see it. Mark others place with //TODO username where it need more works and/or the username is only visible by author/coach/admin... Additional fix the setup sql for MySQL (index too long).

OO-449: refactor user session to work with identity key, make it pop, implements one to one chat, group chat, course chat, remove connect user list, refactor UserRequest to make it an interface

OO-271: refactor the user session management, move the the logic in its own manager, persist the time out values, make the admin GUI a bit better

non-jira :   fix not-saved guipreferences bug.  add "don't ask again" checkbox to resumeController, fix wording in useradmin-> delete userproperties yesNo popup

OO-67: login via RESt doesn't logout the standard session in OpenOLAT, remove the identities cache in UserSession which wasn't used, remove the TemporaryDispatcher

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branch : bps

FXOLAT-193 OLAT-6429 prevent creation of multiple gui prefs and add auto-healing code for broken users

--HG--
branch : uzhFixes711