push deticated FITS header keywords forward to next processing level

[nicHoch]

History and Comment are the only fits header keywords that will be pushed forward (and maybe appended) to the next processing step. All others are recalculated/reset so some important informations might be lost on the next level

Suggestions for pushing forward:

• TRIG_SCA -> copy over
• DATAWARN -> or with current possible DATAWARN