Throw away redo history once a new action is performed
Throw away redo history once a new action is performed

Keep all pieces in a global double linked list such that individual
pieces can be removed.

rychipman/vis,aoloe/vis,aoloe/vis,8l/vis,twinshadow/vis,cpehle/vis,trengrj/vis,twinshadow/vis,cpehle/vis,clehner/vis,8l/vis,trengrj/vis,rychipman/vis,clehner/vis