message fix
further os independence
fix: missing empty bytes in zbf
fix unbound local variable
meet format of zemax manual
clear TODO
fix writeBeamFile
fix writeBeamFile
Merge branch 'bugfix-readBeamFile' of https://github.com/xy124/PyZDDE into bugfix-readBeamFile
Merge pull request #38 from xy124/master

fix #37 (beamfile read and write functions)