Resolve "transparency level of overlay"

Closes #266 (closed)

added 8 commits

• a13e8475...f91e1021 - 5 commits from branch master
• d4b8ea6e - AliasSurface constructor set identified element
• 5d3d5961 - parameter allowing to change admin the opacity
• 3e509859 - opacity of surface is taken from configuration in admin panel

Compare with previous version

unmarked as a Work In Progress

enabled an automatic merge when the pipeline for 3e509859 succeeds

mentioned in commit 4c7f34c3

merged