Currently, when a saved cantor worksheet is opened, the backend is initialized immediately on load. For the use-case where the user only wants to read the worksheets, it's wasting of time and ressources if we start the backeds on load. Also, on systems, where a backend that is used in the stored cantor project is not available, the worksheet cannot be opened.
To improve with respect to these two points, no login has to be done when openning a saved project. All the initializations in Cantor required to show the worksheets correctly (e.g. for the syntax highlighting) need still to be done but no backend systems are initialized. The latter is only done when the user evaluates a command entry (a new or a saved one). In case the backend is not available on the target system where the saved project file is opened, the worksheet is put in the "read-only mode". With this
- the loading of saved files will be much faster
- the user can read the content of the worksheets even if the backend is not available on her/his system.