feat: forest map layout and performance improvements

[skleinjung]

• Place static start location and river.
• Add nonsensical arrangement of random clearings.
• Update color and symbol scheme.
• Dart lizard changes to band-aid performance issues.
• Updates to forest map.
• Improve render performance by culling map tiles and reusing background graphics.
• Improve performance by disabling updates to non-visible map cell tiles.
• Fix bugs in 'startle' behavior keeping creature from immediately moving.
• Fix game freezes caused by attempting to move to non-traversable terrain.
• Fix bug caused when a player moves with keyboard during click-to-move action.
• Improve creation of organic forest clearings.
• Speed up game loop to 30 updates per second.