This merge request brings an addition to the settings by:
Adding a new section in the Settings tab introducing a feature to allow users
to reset all the settings to their default values.
This merge request also brings a fix to:
The setting specifier that is now checked before being used in order to avoid
crashing the application by accessing its variables in the case where
the specifier does not exist.
Some default values that were not properly declared or had the wrong type.
