Change top variable from first to last in inputs

For the Boolean Table implementation, this will allow a nice speed
hack when calculating the cofactor of one variable. If the 'top'
variable is the MSB of the ordered variables, you can just cut
the table in half--one half for top=0 and the other half for top=1.
Rename iter_space to iter_points
Create iter_terms method for iterating max/min terms
Remove all unit tests from boolfunc module
Cleanup
Have iter ones/zeros use top variable & rest