update readme and main.cpp debug messages

src/Core/GameParameters.h

@@ -15,7 +15,7 @@ class GameParameters {
         Player controls;     // the player's controls
         int clearedLines;    // the number of cleared lines
         int level;           // the current level
-        int grade;          // the current amount of points
+        int grade;           // the current amount of points
         int nextQueueLength; // the number of pieces visibles in the next queue
         bool boneBlocks;     // wheter all blocks are bone blocks
         int gravity;         // the gravity at which pieces drop