Brush test file
Add /who and /status commands
Fix saving of files opened in unsupported format

Not all formats that can be read can be written. Pop up
the "save as" dialog in these cases.
Show image loading error message.

Show just the error message without the generic "an error occurred" text.
Replace getConfDir with QStandardPaths
Refactoring: remove application ::getSettings

This function no longer servers any purpose. This change also
necessitated cleaning up toolsettings.cpp