Fix iss#1492

Introduced lcd_strlen() and lcd_strlen_P().
Replaced the old functions where necessary.
Reworked language_ru.h.

Speeded up test for zero length string in cardreader.cpp

Marlin/ultralcd.h

@@ -4,7 +4,8 @@
 #include "Marlin.h"
 
 #ifdef ULTRA_LCD
-
+  int lcd_strlen(char *s);
+  int lcd_strlen_P(const char *s);
   void lcd_update();
   void lcd_init();
   void lcd_setstatus(const char* message);