FX-60: adapt to changes in olatinstaller:  stylesheet "injection" into error-html files (service_not_available.html)

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

OO-76: fix activation of the Notifications Panel in Home, fix missing resume controller for OpenOLAT

OO-1, OO-2 : fix some hardlinked references to the default theme, add sound-files, fix modal-dialog-height

OO-65 : 1. replace default plaintextArea with tinyMCE        2. remove "preview" button  (ALSO for Cluster mode)

OO-59: make cache of assessment lazy loading (the cache stay for ever in memory, and the indexer open all courses, create all assessment caches), use the SingletonEhCacheProvider to have a better picture of the cache usage