[boost] [shifted_ptr] STL required modifications

Ok, If we comment out line 68 of shifted_ptr_test2.cpp in the sandbox and uncomment line 69 we will get a simplified version of the error messages we used to have with std::vector. It is easier this way uncovering the required modifications necessary to make STL user-friendly with smart pointers. I have also made shifted_allocator the way it should be. Yes it is strange replacing pointers to nodes inside containers and I don't see an urgent need for it but this can help unobfusticating the standards regarding pointers to nodes. Thanks, -Phil