Add old behavior of M110 back and combine it with the actual behavior…

… of Prusa firmware >3.12.x

printrun/printcore.py

@@ -416,7 +416,17 @@ def startprint(self, gcode, startindex = 0):
             return True
 
         self.clear = False
-        self._send("M110 N-1")
+
+        '''Reset Gcode line number for printer
+           Actual Prusa firmware >3.12.x needs "M110 N-1"
+           Smoothieware firmware needs "N-1 M110"
+           Old Marlin firmware 1.0.0 needs in addition line checksum
+           self._send("M110 N-1", -1, True) work for Smoothieware and old Marlin firmware.
+           Test for Prusa is needed
+        '''
+        #self._send("M110 N-1") #Prusa firmware >3.12.x
+        self._send("M110 N-1", -1, True) #all in one if Prusa works with "N-1 M110 N-1 + checksum"
+        #self._send("M110", -1, True) #older or other firmware, like Smoothieware + Marlin 1.0 needs checksum in addition
 
         resuming = (startindex != 0)
         self.print_thread = threading.Thread(target = self._print,
@@ -675,7 +685,17 @@ def _sendnext(self):
             if not self.paused:
                 self.queueindex = 0
                 self.lineno = 0
-                self._send("M110 N-1")
+
+                '''Reset Gcode Line number for Printer
+                Actual Prusa firmware >3.12.x needs "M110 N-1"
+                Smoothieware firmware needs "N-1 M110"
+                Old Marlin firmware 1.0.0 needs in addition line checksum
+                self._send("M110 N-1", -1, True) work for Smoothieware and old Marlin firmware.
+                Test for Prusa is needed
+                '''
+                #self._send("M110 N-1") #Prusa firmware >3.12.x
+                self._send("M110 N-1", -1, True) #all in one if Prusa works with "N-1 M110 N-1 + checksum"
+                #self._send("M110", -1, True) #older or other firmware, like Smoothieware + Marlin 1.0 needs checksum in addition
 
     def _send(self, command, lineno = 0, calcchecksum = False):
         # Only add checksums if over serial (tcp does the flow control itself)