Implementation image de "preload". 
Changements dans tous les fichiers pour faire le preload des images au debut du jeu.
Merge branch 'master' of https://github.com/Avangarde/crystal-crush

Conflicts:
	crystal-crush/public_html/js/GamePanel.js
	crystal-crush/public_html/js/LostPanel.js
	crystal-crush/public_html/js/Lvl1.js
	crystal-crush/public_html/js/ScorePanel.js
	crystal-crush/public_html/js/variables.js
Merge branch 'master' of https://github.com/Avangarde/crystal-crush

Conflicts:
	crystal-crush/public_html/js/GamePanel.js
	crystal-crush/public_html/js/LostPanel.js
	crystal-crush/public_html/js/Lvl1.js
	crystal-crush/public_html/js/ScorePanel.js
	crystal-crush/public_html/js/variables.js