Mechanism to render text within the landscape

[kostmo]

See #2190 (review):

would be worth adding a built-in, more streamlined way to include text entities, in cases like this when you want to label things on a world map

and

Yeah, something like this would be nice:

palette:
  - char: 'X'  # {name: "X", display: {char: "X"}, description: ["X"], properties: [known]}