add onstart handler and lazystart event
add onstart handler and lazystart event

masterweb121/lazy-load-xt,ProxiBlue/lazy-load-xt,ressio/lazy-load-xt,josephtan/lazy-load-xt,kavallo/lazy-load-xt,patricknelson/lazy-load-xt,ressio/lazy-load-xt,patricknelson/lazy-load-xt,palimadra/lazy-load-xt,palimadra/lazy-load-xt,josephtan/lazy-load-xt,masterweb121/lazy-load-xt,kavallo/lazy-load-xt,ProxiBlue/lazy-load-xt