* redesign for faster cpu/gpu synch
* load + more async CPU
* use command encoder API and move more ops to use it
* make fence back-end generic + CPU only fence
* faster build
* fix async eval
* fixes + handle temporaries
* fix / improve cpu conv
* remove unused status, fix siblings
* fix extensions
* fix
* fix no cpu build
* format
* comments
* fix perf regression, remove unecessary abort
* fix events, task limit cpu
* fix waiting
* fix donation / temporaries in normalization
