print all quadrants after inserting particles

not only show where the quad lives, but the number of particles, too
we don't need to return found quad for now
destroy couldn't work without initialization ;)
FIXBUG save only pointer to particles

This lead to a memory leak I couldn't find so easily.
Now we have to care ourself about the memory a particle consumes
allocate everything via P4EST_ALLOC

following this, libsc allows us to assert that we freed as much as we
allocated
adjust destroy_fn and enhance readability
remove some DEBUG info and move one print
add a ToDo
removed unnecessary and bug introducing code

saving a particle only means saving a pointer to it
don't forget to destroy our points array

look at todo, this will be really useful as soon, as we can insert more
than one particle at once