Add Codacy to CI?

I recently added [codacy](https://www.codacy.com/) to the `cqparts` CI chain for PRs, and I think it's going quite well.

- What do you think about adding it to `cadquery`s CI?
- Can you suggest a better alternative?

**First Impressions / First Installing**
When first directed codacy toward the `cqparts` repo', it scared me with a terribly low quality score.
But I quickly realised that most of that is knit-picking my less strict formatting of `.md` files, `.js`, `.css`, and other files that aren't really the main "product".

However, that's definitely a worthwhile project in the future: going through the lists of warnings, and either fixing the code, or manually checking them off as OK.

**Advantage for PRs**
It will inform you of unused libraries, bad formatting, and potential security problems.
I tried adding something like:

```python
import subprocess, os
subprocess.Popen(os.environ['foo'])
```

And it failed the test, warning me that this addition could be dangerous.
Then once I added a new commit with those changes removed, the test passed again... it's nifty.

Output is here (while it's still available): https://app.codacy.com/app/fragmuffin/cqparts/commit?bid=10377018&cid=302653800 ; I'm assuming it'll be deleted after some time 'lapses