Change generated comment header for opcodes.go to match Go regexp:
```
^// Code generated .* DO NOT EDIT\.$
```
Fix panic in gen-opcodes.go if no args provided.
Delve is a debugger for the Go programming language. The goal of the project is to provide a simple, full featured debugging tool for Go. Delve should be easy to invoke and easy to use. Chances are if you're using a debugger, things aren't going your way. With that in mind, Delve should stay out of your way as much as possible.