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/PlayerLocal.h

@@ -9,6 +9,7 @@ class PlayerLocal : public Player {
   public:
     // Library Controls
     void loadFile ( Track track ) override;
+    void loadLibrary();
     void scanLibrary() override;
     void updateLibrary() override;
     void editMetadata() override;
@@ -30,4 +31,8 @@ class PlayerLocal : public Player {
       unsigned int currentTrack_;
       db db_;
       std::string musicFolder_ = "data/";
+
+      ht tracks_;
+      ht artists_;
+      ht albums_;
 };