[library/filescanner/spotify] Add library source abstraction and new

"library" thread

- Implement filescanner as a library_source
- Add library source implementation for spotify
- Move process_media_info to library with small adjustments:
  - Remove dependency to F_SCAN_TYPE defines
  - Pass data_kind as parameter
  - Pass media_kind and compilation as parameter if a source forces a
specific value for these
- Move declaration of scan_ffmpeg to library; add
library_add_playlist_info to library

src/library.h

@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2015 Christian Meffert <christian.meffert@googlemail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef SRC_LIBRARY_H_
+#define SRC_LIBRARY_H_
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <time.h>
+
+#include "db.h"
+
+/*
+ * Definition of a library source
+ *
+ * A library source is responsible for scanning items into the library db.
+ */
+struct library_source
+{
+  char *name;
+  int disabled;
+
+  /*
+   * Initialize library source (called from the main thread)
+   */
+  int (*init)(void);
+
+  /*
+   * Shutdown library source (called from the main thread after
+   * terminating the library thread)
+   */
+  void (*deinit)(void);
+
+  /*
+   * Run initial scan after startup (called from the library thread)
+   */
+  int (*initscan)(void);
+
+  /*
+   * Run rescan (called from the library thread)
+   */
+  int (*rescan)(void);
+
+  /*
+   * Run a full rescan (purge library entries and rescan) (called from the library thread)
+   */
+  int (*fullrescan)(void);
+
+};
+
+int
+scan_metadata_ffmpeg(const char *file, struct media_file_info *mfi);
+
+
+void
+library_process_media(const char *path, time_t mtime, off_t size, enum data_kind data_kind, enum media_kind force_media_kind, bool force_compilation, struct media_file_info *external_mfi, int dir_id);
+
+int
+library_add_playlist_info(const char *path, const char *title, const char *virtual_path, enum pl_type type, int parent_pl_id, int dir_id);
+
+void
+library_rescan();
+
+void
+library_fullrescan();
+
+bool
+library_is_scanning();
+
+void
+library_set_scanning(bool is_scanning);
+
+bool
+library_is_exiting();
+
+int
+library_init();
+
+void
+library_deinit();
+
+
+#endif /* SRC_LIBRARY_H_ */