Roadmap for v0.5

[sunxfancy]

I think I should make commands run in real time when I am editing the input file.
Just like what compiler explorer did. Okay, more and more similar. :)

However, there is a few issues to solve:

1. performance - we don't want to print all the IRs immediately since it's so slow to print and parsing.
2. async processing - we want the commands run in background when I am typing so it won't break the editing.
3. lazy processing - If we are opening a window - we just want to see change on that window in real time. Other commands could be delayed.