Serialization: merged SGVector, SGMatrix, Any and SGObejct cereal serialization and added tests.
To do: Serialization of other non-SGObject based classes; Remove and replace old serialization. GPU-data structure serialization/Compatibility with new linalg SGVector/SGMatrix gpu_ptr member. Linalg: Merged SGMatrix and SGMatrix block sum. Other methods are ready to merge: max, set_const, range_fill and scale. To do: Replace old linalg methods. Replace SGVector/SGMatrix methods. Next week: Documentation!
