feature: clear added to the shell

headers/terminal.h

@@ -46,6 +46,7 @@ int terminal_write(const char *data, size_t size);
 int terminal_writestring(const char *data);
 int terminal_writelong(long number);
 void terminal_set_screen(int pos);
+void terminal_clear(void);
 struct key_event terminal_getkey(void);
 void update_cursor(void);
 void move_cursor(int direction);