[Added] Added option "Load-Head-Textures-From-GUIs" in Merchant.yml. Whether to enable reading player head textures from GUIs to save to database. (This feature will be used to fix an issue where player head data could not be saved in versions 1.8.x - 1.12.x.)
[Fixed] Fixed a series of problems in menu usage (a series of problems such as null pointer error, invalid click, etc.)
[Fixed] Fixed some minor bugs. (code logic errors)