[RFC] Amiga/VMS cleanup

The removal of most items was pretty straightforward, but I have one question. I noticed that `runtime/doc/develop.txt` states this:
```
Function names can not be more than 31 characters long (because of VMS).
```
Does anyone know if this is still true? If it's not, I'd like to remove it.
Lost the context of the previous sentence, so this should now be:

    Trailing spaces in filenames ...