added a FastKdTreeMemoryAllocator

Now the fastKdtree is alaways created to a 8 byte aligned adress, as the
memory allocator is used. The memory allocator also gives the method to
allocate 16 byte for a left child and the right child to adress+1
returned by the function "FastKdTree*  NewFastKdTreePair()"

The memory allocator also secure that the whole memory allocation is
in one linear heap element.

Removed the usage of the SAH-strategy in testmain.cpp main(), cause it
failed to compile.