2010-06-29    Speed much improved thanks to B. Swinkels'
                   help in code optimization

2010-05-21    Fixed index inversion in mirror_reflection_qxy
                   New functions to lock Virgo
                   (lockvirgo_plot and error_signals_virgo)

2010-05-12    Fixed problems in maps computations, now tested and
                   giving qualitatively same results as DarkF and Finesse

2010-05-07    Fixed bug in examples (itf.fmod / itf.fmod1)
                   Fixed rotation when computing maps