The changes, in no particular order:

• updated shared code between libraries
• mods now only make a data structure if they do not have existing persistent data
• attempted an optimization for merged crowns
  • merged crowns now iterates through all new instances instead of doing a bunch of with(instances_matching) loops
  • it's probably faster, and should be functionally identical to you, the player, if I did it right
• updated Custom Options' example and template files
• fixed defective string -> number code in Custom Options
• added sprite_save_confined_outlined to merge scripts.mod.gml in preparation for merged enemies
• corrected various script errors in tentacletech.mod.gml
• extralevels.mod.gml now uses the vanilla rad color before levels start to loop
• changed fake mutations.mod.gml's letterboxing to better match the base game (width scaling)
• fixed unobtained mutations showing up in /mskill-scale as undefined
• did a band-aid fix for Lots O' Muts' "neural network" mutation erroring when generating a merged tip
• fixed and optimized custom long arms scaling, while restoring long arms actually getting set as a vanilla mutation
• NTT >= 9944 no longer defaults the 9940 compatibility setting for merged mutations to on
• remade most of the mutation scrolling code, again

There were a few other things that I did in unannounced updates.  I didn't make posts for them because they were small changes, and now I don't remember what they were.

Merged enemies soon.