Implement pawns that walking through 10*10 board

Scala.js was utilized here for UI to provide better demo experience.

See demo implementation here https://aafa.github.io/pawns/

Strategies implemented

Random walker

Walks through the board picking random steps from the list of available ones

Performance is poor and unreliable.

Warnsdorf-kind walker

Uses "visit cornered places first" heuristic with a fallback to random implementation

Tests shows near-polynomial times (O(10*n) is the worst case that was recorded)

RailwayVisitor10

Pre-calculated closed-shape path for 10*10 box that suitable for any starting point. Several Warnsdorf passes were used to get result of a descent quality. Still some cells are visited several times, so there's a field to improve.

Improve on strategy

1. Pre-calculate closed-shaped tour (for any arbitrary box size) and re-use it
   • that visits every cell just ones

Run and test

• sbt test to run tests
• ~fastOptJS to iterate over scala.js ui updates (see ./pawns/target/scala-2.11/classes/index-dev.html)