BP debug tools should check version

[hahnjo]

Describe the bug
The bp?dbg tools are quite handy, but they don't check the BP version resulting in bogus output when mistyping.

To Reproduce

1. Write a dataset with io.SetEngine("bp5") or io.SetEngine("bp4").
2. Open the dataset with the wrong bp4dbg or bp5dbg.
3. Observe bogus data from the incorrect binary format.

Expected behavior
A clear error message should be printed that the BP version is not as expected.

[eisenhauer]

These tools are only meant for developer use and little attention has been paid to error handling. While bp4dbg is relatively complete, bp5dbg is vastly less capable, mostly due to bp5 relying upon FFS and being harder to replicate in pure python. If you submit a PR, it'll be reviewed, but otherwise these tools are improved only as necessary for development.