Remove DrNim

- It is not very useful in its current state.
- No one is actually using DrNim daily in production.
- It failed to attract any hype or active contributors in a long time.
- It often fails to compile or run (tried Windows, Linux, different PC, etc).
- "Cant load Shared Library libZ3".
- DrNim out-of-the-box user experience is not great, you gotta koch it.
- No development-relevant commits in DrNim in a long time, besides typos, documentation fix, etc.
- Nim team work is better spent elsewere, in things used daily by users and companies.
- Less code to maintain, free up more resources to fix important stuff.