setup 2021, remove loop from main

include/advent2021.h

@@ -0,0 +1,58 @@
+#ifndef ADVENT_2021_H
+#define ADVENT_2021_H
+
+void advent2021day01(void);
+void advent2021day02(void);
+void advent2021day03(void);
+void advent2021day04(void);
+void advent2021day05(void);
+void advent2021day06(void);
+void advent2021day07(void);
+void advent2021day08(void);
+void advent2021day09(void);
+void advent2021day10(void);
+void advent2021day11(void);
+void advent2021day12(void);
+void advent2021day13(void);
+void advent2021day14(void);
+void advent2021day15(void);
+void advent2021day16(void);
+void advent2021day17(void);
+void advent2021day18(void);
+void advent2021day19(void);
+void advent2021day20(void);
+void advent2021day21(void);
+void advent2021day22(void);
+void advent2021day23(void);
+void advent2021day24(void);
+void advent2021day25(void);
+
+void (*solutions2021[25])(void) = {
+  advent2021day01,
+  advent2021day02,
+  advent2021day03,
+  advent2021day04,
+  advent2021day05,
+  advent2021day06,
+  advent2021day07,
+  advent2021day08,
+  advent2021day09,
+  advent2021day10,
+  advent2021day11,
+  advent2021day12,
+  advent2021day13,
+  advent2021day14,
+  advent2021day15,
+  advent2021day16,
+  advent2021day17,
+  advent2021day18,
+  advent2021day19,
+  advent2021day20,
+  advent2021day21,
+  advent2021day22,
+  advent2021day23,
+  advent2021day24,
+  advent2021day25
+};
+
+#endif