move callbacks into world

so they can be called from anywhere
testing cases
update comments
translate particle shouldn't take care of quadrant alloc

we handle an already initialized quadrant into the function
precise comment
add searching
fix search problem

create 1-size sc_array holding the mini quad because p4est_search()
wants so
create mini quad for particle
not ready yet..
FIX search callback has to return something

why didn't the compile yelled at me? -Wall was activated...