Reload/Refresh Inline Script During Runtime

We might want to analyze the data dynamically and get the response from the inline analysis directly, just like using ipython during runtime.

[x] Getting error messages from Python and informing users, instead of terminating the whole process.
[x] Load the script and interact dynamically during the code runtime.
[x] Changes maintain throughout the rest of the process
[x] Export the current functions.
[x] Can determine and see what functions will run in the following steps.

~- [ ] Colorful python prompt terminal~ ~- [ ] Indent~

Each inline function execute results/status:

* Inline function execute status:
* yt_inline() ...... finished!
* yt_inline_arg() .. failed
  * Traceback message ...

Enter interactive mode >>>:

>>> if a == "something":
...     print("run somthing")

[x] Scope problem: originally, every inline function are done in inline script's namespace. When we dynamically load and update these functions, we are in global namespace, but we need to be in module's namespace.
- Possible solution:
- [x] use inline_script namespace, for every input from user.
- [x] use exec and pass in sys.modules["inline_script"].__dict__
[ ] yt.enable_parallelism() might run multiple times, if reloading script does not set correctly.
- It's OK to run multiple times, but it's waste of time to do this.
- Possible solution:
- [ ] probably do some checks to see if this MPI is launched already. ~- [ ] Inline script halt once one rank hits an error.~ ~- Possible solution~ ~- [X] [Fast fail with mpi4py]~(https://stackoverflow.com/questions/49868333/fail-fast-with-mpi4py) ~- [ ] coroutine~
[x] Indentation, everything must have the same indentation with the inline script.
- Possible solution:
- [x] if it test each line of code to see they compile or not, then we don't have this problem.
[x] How to tell if it is a valid input?
- Possible solution:
- [x] Test can these line of code can compile or not.
- [ ] IPython?
[ ] Cannot change previous line inputs. (put it to the last to solve)
- Possible solution: ~- [ ] ncurses~ ~- [ ] Erase the current printed console line and To input up arrow key~

[x] Add compile option INTERACTIVE_MODE ~- [ ] Cleaner Makefile.~
yt Finalize
[X] Python objects (freed by Py_Finalize())
[X] Function Status Vector (Don't need to.)
Try, Except, Finally
[x] try: execute inline script
[x] except: only root prints full traceback msg, the other ranks prints no error msg.
- [x] store error msg to somewhere else, so that we can print it in yt_interactive_mode.
- [X] parse traceback msg, make it more readable for user
[x] finally: sync status?
[x] Use %libyt exit for exit. (temp)
libyt command
Should start with %libyt, like %libyt ...
[x] %libyt exit: exit interactive mode, and enter next iteration of simulation.

yt-project / libyt