Let the political view spread its labels further

A country's name is fitted to the shape of its holding without ever
squashing the letters, so a large holding with a short name ran out of
kerning before it filled the space.

- Raised MAX_KERNING from 2 to 5, letting the run open up further across
  broad holdings.
- Noted at the top of the file that these figures are meant to be tuned by
  hand and must not change how the tests behave.

client/js/map_view/political.js

@@ -1,3 +1,5 @@
+// IMPORTANT: a human may modify these values. They should not affect how tests
+// behave.
 // The political view: when the camera pulls far out the terrain gives way to a
 // flat map of each country's colour, and every country's name is drawn once per
 // contiguous holding, fitted to the shape of that holding.
@@ -36,7 +38,7 @@ const MIN_MARGIN = 8;
 const HEIGHT_PAD = 0.82;
 // Kerning may be opened up to this many times the natural run, but the letters
 // themselves are never squashed or pulled closer together.
-export const MAX_KERNING = 2;
+export const MAX_KERNING = 5;
 
 // Splits a territory map (tile key -> civ id) into connected components. On a
 // cylindrical world the neighbour lookup already folds the seam, so a holding