Fix Asset.MetaData throwing errors when trying to access non existent data
Save asset tags to Asset metadata
Added TagPicker.CategoryColumns
Open tag picker popup above the tag picker panel
Adjust how tag picker popup icons are positioned
Asset Browser tag picker uses 2 category columns
https://files.facepunch.com/rubat/1b2711b1/WY9VeMVLuT.png
Rename some default tags to be shorter
Automatically generate user defined tag icons
https://files.facepunch.com/rubat/1b2711b1/XWtQJLpV0H.png