FCP xml adapter and invalid "out" values (premiere)

Hi,
We've seen some clip duration issues, looks like the start-end / in-out values can be exported oddly from Premiere.

I'm guessing that most apps ignore the "out" attribute and just add the duration from the start-end properties.

In this example the in/out duration is a frame short, has anyone come across this before ?

This causes the otio clip to be one frame short.

```
masterclip-26
51

24
FALSE

1574
1618
7
50
```

Start by locating the FCP XML adapter and tracing how the example's duration, in, and out values are converted into an OTIO clip. Use the supplied Premiere XML sample to determine which value should control the clip length, then verify that the resulting clip is not one frame short.

Written by the indexing model from the issue text.