Do not put hidden commands at bottom of command list

This is a fix for #16. This fix makes the entire command list be sorted properly, regardless of whether commands are hidden or not.

Before:

```
COMMANDS
    first                      does stuff first
    sink                       sinks stuff
    sub                        does subby stuff
    ancient-and-deprecated     does stuff the ancient, reallydeprecated way
    old-and-deprecated         does stuff the old, deprecated way
```

After:

```
COMMANDS
    ancient-and-deprecated     does stuff the ancient, reallydeprecated way
    first                      does stuff first
    old-and-deprecated         does stuff the old, deprecated way
    sink                       sinks stuff
    sub                        does subby stuff
```