logic: cleaned up code for SourceGroupSettings and Wizzard

* Flattened sourcegroupsettings class hierarchy by moving cross compilation options to own base class
* QtProjectWizzardContentFlags constructor required correct settings object to reduce the need for type casting
* QtProjectWizzardContentPath constructors required correct settings objects
* moved SourcePaths from SourceGroupSettingsJava to SourceGroupSettingsJavaEmpty because they are not required for Gradle and Maven projects
* removed classpath from maven and gradle source group settings
* reuse code of SourceGroup for "show source files" in wizard

src/lib/settings/SourceGroupSettingsJavaEmpty.cpp

@@ -4,3 +4,40 @@ SourceGroupSettingsJavaEmpty::SourceGroupSettingsJavaEmpty(const std::string& id
 	: SourceGroupSettingsJava(id, SOURCE_GROUP_JAVA_EMPTY, projectSettings)
 {
 }
+
+void SourceGroupSettingsJavaEmpty::load(std::shared_ptr<const ConfigManager> config)
+{
+	SourceGroupSettings::load(config);
+
+	const std::string key = s_keyPrefix + getId();
+
+	SourceGroupSettingsWithSourcePaths::load(config, key);
+	SourceGroupSettingsWithClasspath::load(config, key);
+}
+
+void SourceGroupSettingsJavaEmpty::save(std::shared_ptr<ConfigManager> config)
+{
+	SourceGroupSettings::save(config);
+
+	const std::string key = s_keyPrefix + getId();
+
+	SourceGroupSettingsWithSourcePaths::save(config, key);
+	SourceGroupSettingsWithClasspath::save(config, key);
+}
+
+bool SourceGroupSettingsJavaEmpty::equals(std::shared_ptr<SourceGroupSettings> other) const
+{
+	std::shared_ptr<SourceGroupSettingsJavaEmpty> otherJava = std::dynamic_pointer_cast<SourceGroupSettingsJavaEmpty>(other);
+
+	return (
+		otherJava &&
+		SourceGroupSettingsJava::equals(other) &&
+		SourceGroupSettingsWithSourcePaths::equals(otherJava) &&
+		SourceGroupSettingsWithClasspath::equals(otherJava)
+	);
+}
+
+const ProjectSettings* SourceGroupSettingsJavaEmpty::getProjectSettings() const
+{
+	return m_projectSettings;
+}