tqmerge memory usage is at it's limits

Hello,

For the high-mass HWW analysis, we are running into the issue where we can no longer feasibly merge needed sample folders in the full systematics range. For instance, the merging of ttbar samples after batch submission surpasses 20GB of memory and fails to succeed (even with downmerging and trimmingafterpooling patches applied!). It seems the tqmerge has reached it's limitations, and could use further efficiency improvements to be feasible to use in full run-II analyses and beyond.