REPL. very first impl. lots from Python3.3.2 source

Hi. I tried very naive REPL implementation. 
I bet more work needed, but I have know what you want.

1) Coding style.
2) placing functions, such as "whether be jv_fgest and jv_readline in jv_file.c?" etc.
3) options "z" and "--REPL" is nice for you?
4) Scoping of "def". I expect  when using def in first line of repl, I see that function in second line.
 How do you want it to be achieved?