By default, only use iterative packing if speed is 3 and greater than compilation-speed
Explicit initialisation ftw
Only track interference between unallocated TNs; others just go through the domain directly
Store precolored vertices elsewhere in the interference gaph
Presort vertices in interference graph
Quicker spill choice
No more attempt at warning when vertex in precoloring stack is left uncolored
Microoptimise conflicts-in-sc
Micro-optimize tn-lexical-depth