Feature request: include/exclude pieces by timeline

[IPv6]

first of all thanks for great product and library.
We are started to integrate it to our upcoming fb/mobile game and faced some limitations... we added this features in custom way, but i hope you will agree they can be useful for others as well

here they are:

• Spriter loader ignores Security errors when loading images (only IOErrors are catched)
• IOErrors always throw global exception. It should be possible to set "silent" mode for asset loading (fail can be detected by other means - animation not found in loader for example)
• would be very useful to enable/disable not images but timelines. same image can be used in same animation in different timelines and there is no way to find it out via Spriter api for now
• would be very useful to have named keyframes :) with ability to enum them, move position to them and pause animation on them
• would be handy to enum all animations and all timelines/images inside animation
• Spriter editor does not allow to use jpg files in animations... It`s a pity, because Spriter is great tool for making animated backgrounds

Thanks!