Don't create virtual tables multiple times

src/Album.cpp

@@ -279,7 +279,8 @@ bool Album::createTable(DBConnection dbConnection )
                 "FOREIGN KEY(artist_id) REFERENCES " + policy::ArtistTable::Name + "("
                     + policy::ArtistTable::PrimaryKeyColumn + ") ON DELETE CASCADE"
             ")";
-    static const std::string vtableReq = "CREATE VIRTUAL TABLE " + policy::AlbumTable::Name + "Fts USING FTS3("
+    static const std::string vtableReq = "CREATE VIRTUAL TABLE IF NOT EXISTS "
+                + policy::AlbumTable::Name + "Fts USING FTS3("
                 "title,"
                 "artist"
             ")";

src/AlbumTrack.cpp

@@ -112,7 +112,8 @@ bool AlbumTrack::createTable( DBConnection dbConnection )
             " BEGIN"
             " UPDATE " + policy::AlbumTrackTable::Name + " SET is_present = new.is_present WHERE media_id = new.id_media;"
             " END";
-    static const std::string vtableReq = "CREATE VIRTUAL TABLE " + policy::AlbumTrackTable::Name + "Fts USING FTS3("
+    static const std::string vtableReq = "CREATE VIRTUAL TABLE IF NOT EXISTS "
+                + policy::AlbumTrackTable::Name + "Fts USING FTS3("
                 "title"
             ")";
     static const std::string vtableTrigger = "CREATE TRIGGER IF NOT EXISTS delete_fts_track"

src/Playlist.cpp

@@ -128,7 +128,8 @@ bool Playlist::createTable( DBConnection dbConn )
             "FOREIGN KEY(playlist_id) REFERENCES " + policy::PlaylistTable::Name + "("
                 + policy::PlaylistTable::PrimaryKeyColumn + ") ON DELETE CASCADE"
         ")";
-    static const std::string vtableReq = "CREATE VIRTUAL TABLE " + policy::PlaylistTable::Name + "Fts USING FTS3("
+    static const std::string vtableReq = "CREATE VIRTUAL TABLE IF NOT EXISTS "
+                + policy::PlaylistTable::Name + "Fts USING FTS3("
                 "name"
             ")";
     //FIXME Enforce (playlist_id,position) uniqueness