new methods: Polytope.__add__, Polytope.union, Region.__add__, Region.union
style and convert np.dot(A, B) -> A.dot(B)
replace polytope.union(p1, p2) with p1 + p2
new methods: Polytope.__sub__, Polytope.__and__, Polytope.intersect, Region.__sub__, Region.__and__, Region.intersect
fix docstr
change to property: Polytope.volume, Region.volume
remove function polytope.polytope.dimension, add properties Polytope.dim, Region.dim
new method: Polytope.project
use Polytope and Region methods, instead of polytope functions
bugfix: return result in Polytope.project
remove from top comment polytope functions that are available as methods