A different script to install and update Joplin desktop with features to backup note db etc

NOT for joplin terminal, but might be extended to work for it.



Tested ver. 1.0.120 on Ubuntu 16
Might also work on other Linux distributions

1. Install Joplin desktop by one command,
       basically wrapping the official install script
2. Kill the running Joplin desktop before installation.
3. Backup the Joplin desktop db to the default directory.
4. Create links to the Joplin desktop with version info
       (unavailable for versions perhaps before 1.0.110)