WIP GameObject.Properties
Proof of concept Dynamic Properties sheet
https://files.facepunch.com/ziks/1b3111b1/sbox-dev_5ewZW6QaZ5.png
Nicer integration of dynamic properties with the Action Graph editor
https://files.facepunch.com/ziks/1b3111b1/sbox-dev_JBs2cwHbhM.mp4
Expose setting properties on arbitrary GameObjects
Nicer dynamic property serialization
Fixed build errors
Rename GameObject.Properties to GameObject.UserData, document