COMP: Replace memcpy with std::copy in ImportImageContainer.

This came up as a compiler warning in one of Univ of Iowa's
BRAINS applications.  There was a warning about memcpy over-writing
vtables in itkImportImageContainer.hxx.

The only reason this hasn't caused real problems is that the
usage of ImportImageContainers resize capability is vanishingly
rare, and as far as I know, not covered by ITK regression tests.

At Bradley Lowenkamp's suggestion I replaced memcpy with std::copy.
This usually has no performance penalty; most implementations boil
down to a call to memcpy or memmove for POD.

Since ITK requires that all Pixel types provide operator=, any
compiler errors engendered by using std::copy are actually useful
diagnostics.

Change-Id: I3e1827f9f0eaeb95c8adfc0d668d868aba5cbe21
Merge topic 'ImportImageContainer_rm_memcpy'

2ddacb4 COMP: Replace memcpy with std::copy in ImportImageContainer.