Fix warnings

Summary

Closes #2015 (closed)

Current state of this MR: all warning should be cleaned on the fast build, I created the MR to trigger builds on all platforms and with the packaged remote modules.

Implementation Details

Fixed warning are :

• comparison of two values with different enumeration types in switch statement in mvdImageViewWidget.cxx : QSurfaceFormat and QGLFormat are in practice the same enums, but the compiler can't know that !

• !678 (merged) fixed a warning (returning temporary initializer_list does not extend the lifetime of the underlying array) but created another one (expression result unused, on Clang 6.0). The "unused result" is a dummy initalizer_list used for pack expansion. See for example this article for explanations on this trick.

Copyright

The copyright owner is CNES and has signed the ORFEO ToolBox Contributor License Agreement.

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Check before merging:

• All discussions are resolved
• At least 2 votes from core developers, no vote.
• The feature branch is (reasonably) up-to-date with the base branch
• Dashboard is green
• Copyright owner has signed the ORFEO ToolBox Contributor License Agreement
• Optionally, run git diff develop... -U0 --no-color | clang-format-diff.py -p1 -i on latest changes and commit