supporting TAB key to do text completion

(1)Added memory_op.c
    |- pvPortRealloc()
(2)Support TAB key's function
Bug:the autocomplete can't change the string along with the [TAB] key pressed count increase
renamed send_str() to putstr() and removed the related code in the structure
modified the Makefile to compile the memory_op.c

*Forgot to add to the commit at commit "7a7f"