Call to p2pool::panic causes segfault
There are a few places that call to `panic` as defined here:

https://github.com/SChernykh/p2pool/blob/d23c46ff845cb9568890d96a380d074592613ce5/src/util.cpp#L50-L61

This causes the program to exit with a segfault like this (even if just used with incorrect arguments):

```
2022-05-22 21:29:15.9482 Log started
2022-05-22 21:29:15.9484 P2Pool v2.0 (built with GCC/12.1.0 on May 22 2022)
2022-05-22 21:29:15.9484 P2Pool Invalid wallet address. Try "p2pool --help".
2022-05-22 21:29:15.9484 Log stopped
[2]    1275243 IOT instruction (core dumped)  p2pool --host 127.0.0.1 --wallet 
% 
```

I think this should be a call to `exit(1)`.