Synh DB logic not implemented yet.

1. when the file browser is opened elsewhere, the note cannot be deleted.
2. when we try to open the file which is already opened, opened file will gain focus.

2. controlpressed not refreshed after event done: resolved
3. New feature: rename, and when user is editing new file, asks to change name. Refuse empty string. Until they cancel, or give proper name, dialog keep appears
4. After sotring, delete/open did not work properly in browser: resolved

This is a test push since this branch will not be used anymore. It contains htmleditor and its gradle

JUNIT5 has been added in dependencies in all gradle files. Implemented two unit tests for file management. Fixed bug.