Move display creation from main class to static CDisplay::create()

Display.h

@@ -25,6 +25,10 @@
 
 #include <cstdint>
 
+class CConf;
+class CModem;
+class CUMP;
+
 class CDisplay
 {
 public:
@@ -72,6 +76,8 @@ public:
 
 	void clock(unsigned int ms);
 
+	static CDisplay* createDisplay(const CConf &conf, CUMP *ump, CModem *modem);
+
 protected:
 	virtual void setIdleInt() = 0;
 	virtual void setLockoutInt() = 0;