Bugfix: Store dock clients per screen, not per workspace.

This fixes ticket #12

src/table.c

@@ -42,7 +42,6 @@ void init_table() {
         for (int i = 0; i < 10; i++) {
                 workspaces[i].screen = NULL;
                 workspaces[i].num = i;
-                SLIST_INIT(&(workspaces[i].dock_clients));
                 expand_table_cols(&(workspaces[i]));
                 expand_table_rows(&(workspaces[i]));
         }