Add `OMXPlayerCache` singleton

A possible way to fix application crashing when unloading last omx player video source.

src/Sources/OMXPlayerCache.cpp

@@ -0,0 +1,42 @@
+#include "OMXPlayerCache.h"
+
+namespace ofx {
+namespace piMapper {
+
+OMXPlayerCache * OMXPlayerCache::_instance = 0;
+
+OMXPlayerCache * OMXPlayerCache::instance(){
+	if(_instance == 0){
+		_instance = new ofx::piMapper::OMXPlayerCache();
+	}
+	return _instance;
+}
+
+ofxOMXPlayer * OMXPlayerCache::load(string moviePath){
+	if(_players.find(moviePath) == _players.end()){
+		ofxOMXPlayerSettings settings;
+		settings.videoPath = moviePath;
+		settings.useHDMIForAudio = true;
+		settings.enableTexture = true;
+		settings.enableLooping = true;
+		settings.enableAudio = VideoSource::enableAudio;
+		
+		ofxOMXPlayer * p = new ofxOMXPlayer();
+		p->setup(settings);
+		_players.push_back(p);
+		
+		return p;
+	}
+	
+	_players[moviePath]->restartMovie();
+	return _players[moviePath];
+}
+
+void OMXPlayerCache::unload(string moviePath){
+	if(_players.find(moviePath) != _players.end()){
+		_players[moviePath]->setPaused(true);
+	}
+}
+
+} // namespace piMapper
+} // namespace ofx

src/Sources/OMXPlayerCache.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include "ofMain.h"
+#include "ofxOMXPlayer.h"
+
+namespace ofx {
+namespace piMapper {
+
+class OMXPlayerCache {
+
+	public:
+		static OMXPlayerCache * instance();
+		ofxOMXPlayer * load(string moviePath);
+		void unload(string moviePath);
+
+	private:
+		static OMXPlayerCache * _instance;
+		map <string, ofxOMXPlayer *> _players;
+
+};
+
+} // namespace piMapper
+} // namespace ofx