WIP: more flexible transcode infrastructure
more work on new transcoding, and some model var cleanup
Improved transcode backend, compiling

Needs a better interface, testing
Expose format.transcodable
Expose simple transcode frontend
Evolution for transcoding, schema synchronized
Expose slot.consents list
Improve transcode interface, auto-guess trim
SQL fix in transcode createJob
Fix asset/transcode id on transcoding return
Fix transcode complete slot update wait
Add a few missing execute result checks

Last commit's missing execute reminded me
Merge branch 'transcode'