[libcalamares] Polish model

- make signals consistent in carrying a parameter
- explain why there's no Q_ENUM

src/libcalamares/modulesystem/RequirementsModel.cpp

@@ -34,7 +34,7 @@ RequirementsModel::setRequirementsList( const Calamares::RequirementsList& requi
     m_satisfiedMandatory = std::none_of( m_requirements.begin(), m_requirements.end(), isMandatoryAndUnSatisfied );
 
     emit satisfiedRequirementsChanged( m_satisfiedRequirements );
-    emit satisfiedMandatoryChanged();
+    emit satisfiedMandatoryChanged( m_satisfiedMandatory );
     emit endResetModel();
 }
 

src/libcalamares/modulesystem/RequirementsModel.h

@@ -46,6 +46,7 @@ public:
         NegatedText,
         HasDetails
     };
+    // No Q_ENUM because these are exposed through roleNames()
 
     bool satisfiedRequirements() const { return m_satisfiedRequirements; }
     bool satisfiedMandatory() const { return m_satisfiedMandatory; }
@@ -76,7 +77,7 @@ private:
 
 signals:
     void satisfiedRequirementsChanged( bool value );
-    void satisfiedMandatoryChanged();
+    void satisfiedMandatoryChanged( bool value );
     void warningMessageChanged();
 };