WRG: fix warnings declaration shadows a previous local seen with gcc 8

Fix most of the 39 warnings on pc-christophe (gcc 8):

https://dash.orfeo-toolbox.org/viewBuildError.php?type=1&buildid=332827

I've tagged the MR as 'patch' but also register the branch to the test queue to check if I did not forget any fixable warnings.

added 4 commits

• d80302a7...3e0c0de1 - 3 commits from branch develop
• 2c3445cc - Merge branch 'develop' into warnings_shadow_declaration

Compare with previous version

added 30 commits

• 2c3445cc...e80f1451 - 28 commits from branch develop
• 12ad27b0 - WRG: type qualifiers ignored on cast result type
• d1d6e2d1 - Merge branch 'develop' into warnings_shadow_declaration

Compare with previous version

added 4 commits

• d1d6e2d1...4db72a15 - 3 commits from branch develop
• 5f3aa71e - Merge branch 'develop' into warnings_shadow_declaration

Compare with previous version

merged

mentioned in commit 867f0c1b

mentioned in issue #1722 (closed)

mentioned in commit 78d8c547

added refactoring label