Add DATE-OBS keyword to FITS images

[Alistair M]

CometAlign tool in PixInsight requires the input images to have a DATE-OBS keyword present in the FITS header.

https://archive.stsci.edu/fits/fits_standard/node40.html#SECTION00942210000000000000

According to the link above, the value is a string of format 'YYYY-MM-DDThh:mm:ss'

[Stefan B]

No problem, i will include it in the next Version.

[Stefan B]

Will be included in 1.4.0.2 together with a couple of other fits keywords.