Draw title screen image; desktop game changes

assets gen/images/backgrounds/titleScreen.png resized to powers of two
dimensions. Main menu now draws titleScreen.png in the background.
Reorganized attack animations for easier code implementations in the
future. Renamed new monster sprites for consistency. Draw an X button in
main menu to exit game. Desktop game window is now non resizable and has
title bar removed, making it borderless.
org.lwjgl.opengl.Display.allowSoftwareOpenGL property is now set by code
so that it does not have to be in Celdroids Client Desktop/run.bat. By
passing fullscreen or novsync as arguments to
net.pjtb.celdroids.client.desktop.DesktopGame, game will run in
fullscreen or have uncapped FPS respectively.