logic: generate indexer commands on demand to reduce shared memory consumption

* implemented task for sending IndexerCommands to shared memory on demand
* SourceGroups now return IndexerCommandProviders instead of just a list of indexer commands. This way information can be stored in a compressed format
* merged IndexerCommandCxxEmpty and IndexerCommandCxxCdb
* moved sorting of indexer commands by file size from IndexerCommandList to TaskFillIndexerCommandQueue
* removed obsolete IndexerCommandList class
* wait for IndexerCommandQueue to be filled before starting the indexers
* restart finished indexer processes while indexerCommandQueue is still running
* restart indexer threads as long as there are indexer commands to process
* removed Blackboard::getMutex() and added an atomic update() method

src/lib/project/SourceGroup.cpp

@@ -1,8 +1,14 @@
 #include "project/SourceGroup.h"
 
+#include "data/indexer/MemoryIndexerCommandProvider.h"
 #include "settings/SourceGroupSettings.h"
 #include "utility/file/FilePath.h"
 
+std::shared_ptr<IndexerCommandProvider> SourceGroup::getIndexerCommandProvider(const std::set<FilePath>& filesToIndex) const
+{
+	return std::make_shared<MemoryIndexerCommandProvider>(getIndexerCommands(filesToIndex));
+}
+
 SourceGroupType SourceGroup::getType() const
 {
 	return getSourceGroupSettings()->getType();