Reworked spawnmob command, so while its code changed dramatically, old formats should still work, in most cases.

• Added better support for colored leather armor for spawnmob command. Now you can use
  /spawnmob zombie:boots-leatherboots/125/205/25
  /spawnmob zombie:boots-leatherboots/pink
  /spawnmob zombie:boots-leatherboots/#66ff22
  combinations to colorize leather armor. First one defined in RGB from 0 to 255, second by custom color name and third option is to use HEX color codes.
• Added new custom event as CMIPlayerOpenArmorStandEditorEvent which gets fired before opening armor stand editor which can be canceled in case you don't want for player to edit specific armor stands
• Added support for saddle variable for spawnmob command to spawn in entity with equiped saddle if possible /spawnmob pig:saddle
• Added support for llama with chest for spawnmob command
• Added support for player heads when spawning mobs. Usage: /spawnmob zombie:helmet-head/Notch
• Added support for all boat types for spawnmob command. Usage: /spawnmob boat:bamboo
• Added support for secondary passenger for boats for spawnmob command. Usage: /spawnmob boat ps:sheep ps2:cow
• Added new variable for spawnmob as notpersistent which will spawn mob which will be removed at server restart or chunk unload
• Added new variable for spawnmob as nopickup which will define entity to not being able to pick up items
• Added support for expiration timer for spawned in mobs. This is limited to max 20 minutes and defined in seconds. Usage /spawnmob zombie:ex-120
• Added support for panda main and hidden genes, before it was taking one defined gene and setting for both values, now you can define different ones by using. Example panda:lazy-worried
• Now providing target for the mobspawn command will face spawned monsters towards target
• hp variable got moved inside mobs definition section
• target variable got moved inside mobs definition section
• Updated default locale line for spawnmob command, which only includes only basic example and clickable link to web page with allot better explanation what you can use and how to use it. This will not have effect on existing locale files, only for fresh installs. If you want to get updated one then you will need to remove explanation lines from spawnmob section in your locale file

More information relating to this entire command can be found here https://www.zrips.net/cmi/commands/spawnmob/