Entity locks do not account for locked entities being removed

[penolakushari]

May need to add some checks and entity clearings to the onentityremoved hook or what was it called

[vlazed]

This also happens for parented entities, as well as for new constrained entities or parented entities that get added to the UI (e.g. in multiplayer, select an entity, and have someone weld things to it). This necessitates hooks for entities getting constrained/parented