NOTES

 - merged https://github.com/non/spire/pull/672 sbt-1x

div -> fields, division rings

euclidean -> defined
floor -> round toward -inf
truncate -> round toward 0

equotmod, equot, emod
fquotmod, fquot, fmod
tquotemod, tquot, tmod

-7 /% 5
  = (-1, -2)  truncated (% uses sign of dividend) -- jvm
  = (-2, 3)   floor (% uses sign of divisor)