Release v0.2.0

new features:

• sprite.Touching, BounceOffEdge
• sprite.GoBackLayers, GotoFront
• playSound, stopAllSounds
• fs.Open(path) (Dir, error), support localFS, zipFS(zip://xxx) and httpZipFS (hzip://xxx or hzips://xxx).
• load Game/Sprite from resource (see fs.Open), see spx.Load(game) & game.Load(sprite)
• game.Run
• draw
• input (keyboard, mouse)
• tutorial: weather (not completed)

changes:

• FileSystem => fs.Dir