Add a couple utility functions

Forgot to commit this new file in a previous commit

src/util.zig

@@ -0,0 +1,7 @@
+pub fn max(comptime T: type, a: T, b: T) T {
+    return if (a > b) a else b;
+}
+
+pub fn min(comptime T: type, a: T, b: T) T {
+    return if (a < b) a else b;
+}