Implement basic generation and printing

I expect this will probably generate some impossible puzzles, but I'll
deal with that later.

main.c

@@ -16,7 +16,21 @@
  * <https://www.gnu.org/licenses/>.
  */
 
+#include "sud.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
 int main(void)
 {
+	unsigned seed = time(NULL);
+	printf("Seed: %u\n\n", seed);
+	srand(seed);
+
+	struct sudoku sud;
+	gen(&sud);
+	print(&sud);
+
 	return 0;
 }