Cache All Comps When Idle

Add a checkbox to the "Cache Frames When Idle" preferences to start caching the other comps in the project after the Comp in focus has been cached.

With the profliferation of large cache drives and spare cpu cycles these days if a computer is idle for awhile, it would be greatly beneficial to have After Effects chugging away at all the other comps in the project if there is nothing else going on. I also realize that is potentially a lot of data and cpu power to be used so having this turned off by default might be wise.