First pass at a sudoku solver: Puzzle Import

Imports a puzzle from a string and displays the restricted puzzle.

solver.cpp

@@ -0,0 +1,11 @@
+#include <iostream>
+
+#include "solver/puzzle.h"
+
+int main(int argc, char** argv) {
+  Puzzle puzzle = Puzzle::FromString(
+      "3..4.162.1...8.4....5.2.83..578........7..5.3..29.4..748.53..1.2.3.9...."
+      ".7...6.9.");
+  std::cout << "https://tiramisu.one/sudoku.html?p=" << puzzle.CurrentState()
+            << "&m=" << puzzle.PencilMarkState() << std::endl;
+}