Refactor containers and library loading

Replace trackPtr with raw Track* pointers in HashTable, add loadLibrary
to PlayerLocal, remove unused File helpers, and fix broken artwork/artist
SQL bindings.

include/File.h

@@ -12,11 +12,9 @@ class File {
     public:
         Track importFile( const std::string& filePath );
         void scanFolder( const std::string& folderPath, std::vector<Track>& tracks );
+        void updateLibrary();
         void readFileTag( Track& t );
         TagLib::VariantMap importArtwork( Track& t );
-        std::string parseFiletype( const std::string& path );
-        void updateLibrary();
-        uint64_t hashString( Track t );
 
     private:
         std::string path_;