Make Alignable trait a requirement for optical trait

Will help to make sure that all new nodes will be able to be aligned. May be problematic with a group...

changed milestone to %v0.6

added discussion label

assigned to @u.eisenbarth

Doesn't work for reference nodes as well. So, we have to add this for each node...

created branch 313-make-alignable-trait-a-requirement-for-optical-trait to address this issue

mentioned in merge request !210 (merged)

mentioned in commit bf0cb670

closed with merge request !210 (merged)