logic: added Gradle project setup (issue #379)

* added implementation for Gradle project setup (icon is still missing)
* refactored project loading/saving and SourceGroupSettings
* removed long deprecated Cxx UseSourcePathsForHeaderSearch option

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src/lib/project/SourceGroup.cpp

@@ -1,5 +1,7 @@
 #include "project/SourceGroup.h"
 
+#include "settings/SourceGroupSettings.h"
+#include "utility/file/FileManager.h"
 #include "utility/file/FilePath.h"
 
 SourceGroup::~SourceGroup()
@@ -21,6 +23,18 @@ bool SourceGroup::prepareIndexing()
 	return true;
 }
 
+void SourceGroup::fetchAllSourceFilePaths()
+{
+	m_sourceFilePathsToIndex.clear();
+	FileManager fileManager;
+	fileManager.update(
+		getAllSourcePaths(), 
+		getSourceGroupSettings()->getExcludePathsExpandedAndAbsolute(), 
+		getSourceGroupSettings()->getSourceExtensions()
+	);
+	m_allSourceFilePaths = fileManager.getAllSourceFilePaths();
+}
+
 void SourceGroup::fetchSourceFilePathsToIndex(const std::set<FilePath>& staticSourceFilePaths)
 {
 	for (const FilePath& sourceFilePath: m_allSourceFilePaths)