users with permission edit_help_texts are allowed to select edit help
texts from menu and enter texts for all event fields. Other users will
see help texts as tooltips. This allows to provide help to users
depending on your workflow. help texts are saved by project and studio.
On copying events from another studio selection will be saved.
The next time one wants to copy saved presets are preselected.
This simplifies to frequently rebroadcast shows from another project.
User sessions will be stored in database and not in files anymore.
CGI::Session is not used anymore for this purpose. The new module
user_sessions.pm provides functions on new database table user_sessions.