in case of dynamic regions we need to forward_transform the point since
the point is generated in region space and also the match* functions
perform an inverse_transform to bring the given point into the region space
for inside testing;
note that there is still some issue for dynamic regions:
- in case of subdomain_flag=true the region bounding box in region space
is tested against the subdomain bounding box in global space;
- if the transformed region has no intersection with the subdomain, no
point can ever match the exit condition of the while loop
(for static regions this is usually avoided by calculating the volume fraction
of the region in each subdomain via Region::volume_mc(), not calling the
generate_random* functions if the volume fraction is below a certain treshold)
