Merge remote-tracking branch 'origin/bone-multilink'

* origin/bone-multilink:
  Inherrit width of previous bone when inserting new one
  Add forgotten file to Makefile.am
  Fix bug with "Link to Skeleton" action
  Add amount parameter for skeleton layer
  Use smaller width for bones by default
  Add possibility to load previous format of BoneLink
  Fix 'link to skeleton' action
  Fix bone width ducks (rotate 90 deg)
  Visualize bone width
  Implementation of Link to skeleton (Bugs!)
  Draft of Action::ValueDescSkeletonLink
  Draft of ValueNode_Bone::have_influence_on()
  Revert "Add list of bones into ValueNode_BoneLink"
  Revert "Fix ValueNode_BoneLink"
  Revert "Update "Link to Bone" action"
  Write pseudo-code implementation of "Link to Skeleton" action
  Ass "Link to Skeleton" action. Not works (its functionality is copied from "Link to Bone").
  Enable loading for bone files of previous format
  Introduce "BoneWidth" and "Bone Tip Width" parrameters. Add handles for them.