Add a checkRemove method to CmdGeneric.
It is called by asyncqueue if remove flag is true, to let the newly added command check if it wants its predecessors to be removed. Default is to always allow. Only implemented in CmdPlaytreeUpdate: only remove previous commands if they are about the same item. -> Limit excess updates to playtree (There are some debug messages left in this commit, will remove later)
Showing with 39 additions and 8 deletions