Render map preview on scenario selection screen

[kostmo]

Closes #353
Also towards #1415

Also adds a new top-level command to render a scenario map to the console.

Most of the work for this feature entailed identifying the subset of GameState that is actually needed for rendering the world, so that the required information can be retrieved from just the Scenario rather than having to instantiate an entire GameState.

Potential follow-ups

• There is some noticeable lag when using the up/down arrow to navigate to any of the largely "procedurally generated" scenarios, e.g. classic or creative. May want to do caching of some kind. The other "challenge scenarios" render without perceptible delay.
• The heuristic for choosing the view center could be improved, possibly by defining new "hints" as part of the scenario schema.
• Rendering to the console could be augmented with color.
• Could render to other image formats like PNG or SVG
• account for a user-selected seed in the scenario launch parameters dialog

Demos

Scenario selection preview

Command-line map rendering

~/github/swarm$ scripts/play.sh map data/scenarios/Challenges/ice-cream.yaml
              
              
              
              
           OO 
▒▒▒ ▒▒▒▒  OOOO
┌─┐▒┌──┐  MMMM
│B   V6│  \ZZ/
└──────┘   \/ 

and

stack run -- map data/scenarios/Challenges/hackman.yaml
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
▒••••••••••▒••••••••••▒
▒o▒▒▒•▒▒▒▒•▒•▒▒▒▒•▒▒▒o▒
▒•▒▒▒•▒▒▒▒•▒•▒▒▒▒•▒▒▒•▒
▒•••••••••••••••••••••▒
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▒▒▒▒▒•▒▒▒▒ ▒ ▒▒▒▒•▒▒▒▒▒
    ▒•▒         ▒•▒    
▒▒▒▒▒•▒ ┌──=──┐ ▒•▒▒▒▒▒
     •  │     │  •     
▒▒▒▒▒•▒ └─────┘ ▒•▒▒▒▒▒
    ▒•▒         ▒•▒    
▒▒▒▒▒•▒ ▒▒▒▒▒▒▒ ▒•▒▒▒▒▒
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▒o••▒•••••••••••••▒••o▒
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[xsebek]

LGTM! 👍 I have a few nitpicks and questions, but overall I like the improvements and the refactoring. 🙂

I can look into terminal color output - there was a library for pretty Doc, but I think it only had basic colors.

[byorgey]

When I do stack run -- map data/scenarios/classic.yaml I get no output. Do you know what's going on there?

[kostmo]

When I do stack run -- map data/scenarios/classic.yaml I get no output. Do you know what's going on there?

Yep, had a size zero area of the map. Added a default for this case now.