listfiles subcommand for dbx: Display the list of source files

Format

listfiles [loadmap-index]

The listfiles subcommand displays the list of files associated with each module in the load map.

If the listfiles subcommand is used without arguments, the files for every module in the load map will be listed.

The listfiles subcommand can be run only while the dbx debug program is running.

To list all files in all modules, enter:
```
listfiles
```
To list the files only for module with index 0 in the loadmap, enter:
```
listfiles 0
```

The listfuncs and map subcommands.