Migrate some members of the Player class to smart pointers

1. Moves the mutex and mixer channel members to unique pointers
2. Moves the trackFile to a weak pointer
3. Move member initialization to the class definition

This class still retains a raw *cd member, however fixing this
ripples up to the array of [26] CD images, and across more
code that generically deals with mount points; so this work
remains to do.

include/mixer.h

@@ -106,6 +106,18 @@ MixerChannel * MIXER_FindChannel(const char * name);
 /* Find the device you want to delete with findchannel "delchan gets deleted" */
 void MIXER_DelChannel(MixerChannel* delchan); 
 
+// A smart pointer deleter for MixerChannel objects
+// Use-case:
+// std::unique_ptr<MixerChannel, MixerChannelDeleter> myChannel;
+// myChannel.reset(MIXER_AddChannel(...));
+//
+struct MixerChannelDeleter {
+	void operator()(MixerChannel *channel) {
+		if (channel)
+			MIXER_DelChannel(channel);
+	}
+};
+
 /* Object to maintain a mixerchannel; As all objects it registers itself with create
  * and removes itself when destroyed. */
 class MixerObject{

include/support.h

@@ -27,11 +27,27 @@
 #include <string.h>
 #include <string>
 
+#include <SDL.h>
+
 #ifdef _MSC_VER
 #define strcasecmp(a, b) _stricmp(a, b)
 #define strncasecmp(a, b, n) _strnicmp(a, b, n)
 #endif
 
+// A smart-pointer deleter for SDL-Mutex objects.
+// Use-case example:
+// std::unique_ptr<SDL_mutex, SdlMutexDeleter> myMutex;
+// myMutex.reset(SDL_CreateMutex());
+//
+struct SdlMutexDeleter {
+	void operator()(SDL_mutex* mutex) {
+		if (mutex)
+			SDL_DestroyMutex(mutex);
+	}
+};
+
+// Returns the filename with the prior path stripped.
+// Works with both \ and / directory delimeters.
 std::string get_basename(const std::string& filename);
 
 // Include a message in assert, similar to static_assert: