Merge pull request #1848 from MRprusa3d/PFW-853

recovery from "Stop()"

Firmware/cardreader.cpp

@@ -242,6 +242,7 @@ void CardReader::startFileprint()
   {
     sdprinting = true;
 	paused = false;
+     Stopped = false;
 	#ifdef SDCARD_SORT_ALPHA
 		//flush_presort();
 	#endif

Firmware/cardreader.h

@@ -161,6 +161,7 @@ private:
   void flush_presort();
 #endif
 };
+extern bool Stopped;
 extern CardReader card;
 #define IS_SD_PRINTING (card.sdprinting)