implement point format 6, 7, and 8 (only) support

[hobu]

@abellgithub not quite sure if this is what we want, but it is a start.

[hobu]

This is ready for review. It is a combo of things:

• Allow the user to set --format to 6, 7, or 8 for single_file
• Complete extra bytes support
• Add the stats VLR and update the info VLR with pointers to it

[hobu]

If you're not and a user is selecting, say, PDRF 6, but has Red, it should be written as an EB field.

I disagree with this idea for behavior. First, if we promote Red to EB fields, it will compress much worse than if the user uses the correct PDRF. There must be a way to strip off the color fields. Otherwise, why bother having COPC support 6, 7, and 8. Maybe just have COPC only support 8 (I don't hate this idea. If there's no values in the color fields, they compress to nothing).

Maybe it would be useful for the user to provide a list of fields they want dropped or a list of fields they want kept as part of a conversion (using PDAL dimension ID names).

[hobu]

This is ready to merge, but there will need to be updates after the next lazperf release to have this code use the (replicated) VLR definitions in hobuinc/laz-perf#102 Those of course are dependent upon COPC specification being complete.

[abellgithub]

I can merge this, but I'd like to remove the COPC VLR stuff. That means that CI will fail because you're pulling lazperf from Conda, but I kinda don't care since Untwine isn't really something that's distributed. I have a few small changes that I'd like to make but I can do them after merge.

Let me know.

[hobu]

I can merge this, but I'd like to remove the COPC VLR stuff.

Yeah, that's fine. Update the private members to use the laz-perf definitions and we can roll out the new release of laz-perf.