heado and tailo raise EarlyGoalErrors
use conso in eq_comm2
tests for eq_assoc2
eq_comm2 tests commutivity
remove opo from new eq_assoc/comm
simplify assocunify
seteq unifies within tuples
remove debug code
eq_assoccomm2 added
expr_test works

assocunify expands eq
eq_assoccomm2 propagates itself as default eq
more tests