[WIP][FOLD] Calculate composed_quality
[WIP][FOLD] Address rounding issues:
* Avoid using math when we can get away with it.
* When we can't avoid it make sure we don't sacrifice accuracy.
* Restructure bridge handling.
* Cleanups.
[WIP][FOLD] Work:
* Remove process_order_bridged and process_order_direct
* Remove some unneeded debug code, assert invariants
* Misc. cleanups
* It's 1AM, three items are enough.
[WIP][FOLD] Work:
* Use composed_quality instead of multiplication operator
* Factor out some common code from bridged and direct transactors
* Cleanups