Refactoring for shogun::memcpy

[lambday]

We recently introduced a wrapper shogun::memcpy in shogun/lib/memory.h to be used instead of memcpy calls in Shogun. This method in turn calls std::memcpy as of now. But the goal was to be able to change this to a different implementation later, if possible, that instantly applies Shogun-wise without touching the rest of Shogun.

So, the task is to replace all existing memcpy calls with this newly introduced shogun::memcpy. However, in order to avoid possible errors due to namespaces, we'd like to rename our wrapper method to sg_memcpy first.

Very simple find/sed task for on boarders :)

[lambday]

Done. Closing.