improve sexp code for obtaining pitch/bank/heading with the following changes: 1) use an alternate algorithm for extracting angles from an orientation matrix 2) properly round floats to integers when converting to degrees

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@11180 387891d4-d844-0410-90c0-e4c51a9137d3