rename x/v to var for consistency
rename try_simplify to complement_simplify
var to var_count
tweak redundant conditionals for no good reason
change convention of complement_simplify to return NULL on failure
tweaking conditional structure in var_stats
cache array dereference
rename pos_co and neg_co and document allocation
fixup variable references
add size to printf call
employ unary minus
tweak variable names
move ALL THE THINGS
true and false cofactors
m and n to b and g
remove duplicated function negate/invert
fixup uses of set_true/set_false to set_val