fixed broken includes

io/math.cpp

@@ -1,7 +1,9 @@
 #include "math.h"
 
+#include <QtMath>
+
 int lerp(int a, int b, double t) {
-    return ((1.0 - t) * a) + (t * b);
+    return qRound(((1.0 - t) * a) + (t * b));
 }
 
 double double_lerp(double a, double b, double t) {