Fix: as_las_string_lossy should ignore anything after the first null character

[tobias93]

I just came across a las file with the following Extra-Attributes VLR:

Vlr {
    user_id: "LASF_Spec\0\0\0\0\0\u{18}\0",
    record_id: 4,
    ...
}

The user_id is not properly filled with null characters (see the \u{18} hidden in there...). In this case, as_las_string_lossy currently returns the full string including all null characters. This results in the extra-bytes VLR not being detected correctly in my own code. Most other tools like LasTools or CloudCompare seem to have no problem with this and just ignore anything after the first null character. I changed as_las_string_lossy to work this way, too. Now as_las_string_lossy correctly parses above user id as "LASF_Spec".

[gadomski]

Thanks so much for the fix!! Really appreciate it. https://github.com/gadomski/las-rs/releases/tag/v0.9.3

[tobias93]

Hey, thanks for replying (and merging) so quickly!