feature: Precedence level location in PEG_TRACE

Be similar to:
```
[PEG_TRACE] Entering level 0 at 1:1
[PEG_TRACE] Entering level 1 at 1:3
[PEG_TRACE] Leaving level 1 at 1:3 to 1:5
[PEG_TRACE] Leaving level 0 at 1:1 to 1:5
```

This may be very helpful for trace debugging