What each rule costs, measured with the RIOT timer

fragment    cycles   bytes what it is
base             0       - the preamble on its own: a step number and nothing else
twelve          12       - twelve cycles of nothing, to prove the instrument
path            18      13 one step of a path written down in a table
chase           19      15 one step towards something, when it has to move
chaseno         17       - the same test, when it is already there
rand            22      19 one step either way, out of the shift register
dispatch        33       - reaching a rule through a pointer, and coming back
box             19       - are the two of them within eight columns of each other
