Minor coverity issue fixes

Minor coverity issue fixes

Fix some minor coverity issues that might has meanful

1. Implement missing move operation.
2. Remove float equal checks by ==, != operator.
3. Remove useless std::move.
4. Remove const keyword for function return value.
5. Resolve some value has same name.
6. Use referenced iterator so we don't copy value.
7. Remove cyclic header include (a.k.a gltf-loader.h -> scene3d-view-impl.h -> gltf-loader.h)

Change-Id: I57ad541310b43413ee0d52b1f8c56a95df12bbd9
Signed-off-by: Eunki, Hong <eunkiki.hong@samsung.com>