Moved LCD initialization out of constructor

Since the class "MainMenu" was used within a static variable the
initialization of the object (constructor call) was done before Arduino
library startup. It always caused a crash when using AVRStudio with
JTAG debugger (caused from calling the LCD initialization / the lot of
I/O work / the stack used during this calls). By moving the LCD_INIT
out of the constructor and using an explicit call inside of Arduino
setup() implementation immediately fixed all problems and the JTAG
debugger runs fine.

Marlin/ultralcd.pde

@@ -99,6 +99,9 @@ FORCE_INLINE void clear()
 void lcd_init()
 {
   //beep();
+  #ifdef ULTIPANEL
+    buttons_init();
+  #endif
   
   byte Degree[8] =
   {
@@ -306,10 +309,6 @@ MainMenu::MainMenu()
   displayStartingRow=0;
   activeline=0;
   force_lcd_update=true;
-  #ifdef ULTIPANEL
-    buttons_init();
-  #endif
-  lcd_init();
   linechanging=false;
   tune=false;
 }