Resolve "Robust remove() API"

implementing #239 (closed)

changed milestone to %IRI release

added Agreement required bug labels

added 6 commits

• 89bea1fe - getChildrenList now returning a const ref and using removeChildren() in all remove functions
• 4b75206e - trajectory function working with const iterators
• 34e0918e - small changes
• 3bd767b8 - added assertions in link() checking not removing
• bee2317d - removed call to getTrajectory()->updateLastFrames() (automatically called before)
• d655fcc1 - added optional viral_remove_empty_parent false by default

Compare with previous version

changed the description

unmarked as a Work In Progress

enabled an automatic merge when the pipeline for d655fcc1 succeeds

merged

mentioned in commit 90b51835