1.2.0

• Row-mean variance test for serial correlations LSSTTD-1478 #109, LSSTTD-1492 #111
• PTC fixes to use np.mean LSSTTD-1482 #110
• Corner raft mosaic work LSSTTD-1493 #112, LSSTTD-1496 #114
• Use TSEQNUM instead of SEQNUM in flat gain stability test LSSTTD-1494 #113
• Report max_observed_signal instead of full_well and add ptc_threshold LSSTTD-1497 #115