fix for HalfSpaceBV compound

Added one unknown float to the end of "HalfSpaceBV" compound as it seems that it has four unknown bytes after "Center". Problem reported at niftools forum http://niftools.sourceforge.net/forum/viewtopic.php?p=28704#p28704
Fixed error in Tangents and Bitangents lines.
Merge pull request #16 from ttl269/feature/HalfSpaceBV-compound-fix

fix for HalfSpaceBV compound