Import %on feature from 0.92.3

Unike $Ne which give current extruder if more than 1 extruder, %on give
1 even only 1 extruder

src/ArduinoDUE/Repetier/ui.cpp

@@ -1514,6 +1514,11 @@ void UIDisplay::parse(const char *txt,bool ram)
                 addInt(Printer::feedrateMultiply, 3);
                 break;
             }
+            if(c2 == 'n')
+            {
+                addInt(Extruder::current->id + 1, 1);
+                break;
+            }
             // Extruder output level
             if(c2 >= '0' && c2 <= '9') ivalue = pwm_pos[c2 - '0'];
 #if HAVE_HEATED_BED

src/ArduinoDUE/Repetier/uimenu.h

@@ -18,6 +18,15 @@
 #if !defined(_UI_MENU_H)
 #define _UI_MENU_H
 
+/*moved to uilang.h
+#define cUP "\001"
+#define cDEG "\002"
+#define cSEL "\003"
+#define cUNSEL "\004"
+#define cTEMP "\005"
+#define cFOLD "\006"
+#define cARROW "\176"
+*/
 /*
 The menu configuration uses dynamic strings. These dynamic strings can contain
 a placeholder for special values. During print these placeholder are exchanged
@@ -93,6 +102,8 @@ random stuff
 %oC : Output level current extruder
 %ob : Output level heated bed
 %PN : Printer name
+%on : current extruder number (1,2,3...)
+%Ne : current extruder number (1,2,3...) if Num extruder >1 , else nothing
 
 stops
 %sx : State of x min endstop.