[galaxy-commits] commit/galaxy-central: greg: Add the ability to chain Galaxy tools into a lineage of tool versions. This enables workflows and the rerun button on history items to work when a new version of a tool is loaded into the Galaxy tool panel. Version information for tools included in tool shed repositories is maintained for each changeset revision in the tool shed, and this information can be retrieved from the Administrative "Manage installed tool shed repositories" menu item for installed tool s