Scripting: Access Terrain Properties

[eishiya]

Unless it's just not documented, scripting appears to have no way to access the properties set on a Terrain, only those on a Terrain Set (WangSet). WangSet.colorName(index) and WangSet.setColorName(index, name) provide a way to interact with the Terrain name, but there seems to be no way to get/set the display colour and custom properties for a given Terrain.

This means Terrain custom properties can't be used to affect script behaviour (e.g. I can't make a custom Terrain tool that only modifies specific Terrains based on their custom properties), and scripts can't copy Terrains fully (for e.g. importing terrains to a metatileset, or writing out to a custom format).

Edit: There is a similar problem with the imageTile - it can be set for the WangSet, but there's no way to access/set it for a Terrain/WangColor.

[eishiya]

Closing as duplicate of #2663