Fix ECHOPAIR ambiguity

- Also patch up some warnings

Marlin/vector_3.h

@@ -37,7 +37,7 @@ struct vector_3
 	float get_length();
 	vector_3 get_normal();
 
-	void debug(char* title);
+	void debug(const char title[]);
 	
 	void apply_rotation(matrix_3x3 matrix);
 };
@@ -52,7 +52,7 @@ struct matrix_3x3
 
 	void set_to_identity();
 
-	void debug(char* title);
+	void debug(const char title[]);
 };