A simple edit to Robin Kuiper's Combat Tracker API script for Roll20 that allows rolling with advantage on the 5e OGL sheet, adding die bonuses to initiative, whispering npc rolls to the GM only, and adding a picture of the token to chat announcements among other small changes.
When trying to add this script to Roll20, click the RAW button before copying. Press Ctrl+A to select the whole text then Ctrl+C to copy it. Go to your game settings/API/New Script and press Ctrl+V to paste the script into the textbox. Name the file whatever you want and make sure to click the "Save Script" button at the bottom of the page.