Fix more element source file includes

src/elements/repl.cpp

@@ -1,4 +1,4 @@
-#include "simulation\Element.h"
+#include "simulation/Element.h"
 
 int update_REPL(UPDATE_FUNC_ARGS) {
 	int r, rx, ry, ri;

src/elements/tron.cpp

@@ -1,4 +1,4 @@
-#include "simulation\Element.h"
+#include "simulation/Element.h"
 
 /* TRON element is meant to resemble a tron bike (or worm) moving around and trying to avoid obstacles itself.
  * It has four direction each turn to choose from, 0 (left) 1 (up) 2 (right) 3 (down).