Add a settings.conf option to disable "Cancel" button

In some cases, e.g. when calamares is used as an "initial setup" tool,
we may want to user to go through all the configuration steps in order
to end up with a usable system.
Therefore, disabling the "Cancel" button can be useful in this case.

This commit adds an option to settings.conf which disables this button
when set to "true". If the option is not present in the settings file,
the default behavior ("Cancel" button enabled & visible) is enforced.

Signed-off-by: Arnaud Ferraris <arnaud.ferraris@collabora.com>

src/libcalamares/Settings.cpp

@@ -81,6 +81,7 @@ Settings::Settings( const QString& settingsFilePath,
     , m_debug( debugMode )
     , m_doChroot( true )
     , m_promptInstall( false )
+    , m_disableCancel( false )
 {
     cDebug() << "Using Calamares settings file at" << settingsFilePath;
     QFile file( settingsFilePath );
@@ -183,6 +184,7 @@ Settings::Settings( const QString& settingsFilePath,
             m_brandingComponentName = requireString( config, "branding" );
             m_promptInstall = requireBool( config, "prompt-install", false );
             m_doChroot = !requireBool( config, "dont-chroot", false );
+            m_disableCancel = requireBool( config, "disable-cancel", false );
         }
         catch ( YAML::Exception& e )
         {
@@ -245,5 +247,11 @@ Settings::doChroot() const
     return m_doChroot;
 }
 
+bool
+Settings::disableCancel() const
+{
+    return m_disableCancel;
+}
+
 
 }