move ui_rand to cDialog

src/dialogxml/dialogs/dialog.cpp

@@ -41,6 +41,7 @@ const short cDialog::BG_DARK = 5, cDialog::BG_LIGHT = 16;
 short cDialog::defaultBackground = cDialog::BG_DARK;
 cDialog* cDialog::topWindow = nullptr;
 void (*cDialog::redraw_everything)() = nullptr;
+std::mt19937 cDialog::ui_rand;
 
 std::string cDialog::generateRandomString(){
 	// Not bothering to seed, because it doesn't actually matter if it's truly random.

src/dialogxml/dialogs/dialog.hpp

@@ -20,6 +20,7 @@
 #include <exception>
 #include <functional>
 #include <deque>
+#include <random>
 
 #include "ticpp.h"
 #include "dialogxml/keycodes.hpp"
@@ -70,6 +71,7 @@ class cDialog {
 	std::vector<std::pair<std::string,cTextField*>> tabOrder;
 	static cDialog* topWindow; // Tracks the frontmost dialog.
 	static bool initCalled;
+	static std::mt19937 ui_rand;
 public:
 	static void (*redraw_everything)();
 	/// Performs essential startup initialization. Generally should not be called directly.