Sort regression test reporting by absolute percentage change

[timothy-nunn]

Currently:

WARNING  test_process_input_files:test_process_input_files.py:113 eq_con060           	        -0	  1.88e-07	    100.00
WARNING  test_process_input_files:test_process_input_files.py:113 eq_con011           	 -7.42e-11	    -5e-11	     32.68
WARNING  test_process_input_files:test_process_input_files.py:113 eq_con062           	 -3.39e-08	 -3.13e-08	      7.47
WARNING  test_process_input_files:test_process_input_files.py:113 eq_con035           	 -1.95e-08	 -1.84e-08	      5.49
<... loads of 0.0% changes ...>
WARNING  test_process_input_files:test_process_input_files.py:113 eq_con015           	  -2.9e-07	 -2.98e-07	     -2.58
WARNING  test_process_input_files:test_process_input_files.py:113 eq_con081           	 -5.67e-08	 -5.93e-08	     -4.64
WARNING  test_process_input_files:test_process_input_files.py:113 eq_con025           	   9.5e-09	  8.65e-09	     -8.92
WARNING  test_process_input_files:test_process_input_files.py:113 eq_con027           	  8.29e-08	   7.4e-08	    -10.74
WARNING  test_process_input_files:test_process_input_files.py:113 eq_con026           	  4.33e-08	  2.88e-08	    -33.31
WARNING  test_process_input_files:test_process_input_files.py:113 eq_con030           	  -1.1e-09	 -4.35e-09	   -294.57

Ordering by the absolute value will ensure changes with a large magnitude are presented first.