Added GAIN variable

Created German translation

Created a German translation file for the network website.
"DE" is the 2-letter ISO country code for Germany.

Added Serbian language web-support

Add files via upload

Add Arabic language to webpanel

Web panel

This reverts commit d21bcba550.

Changed JPG to PNG, invert nighttime Meteor M2 images and fixed timezone issues

I've changed the last line which saves the image from JPG format to PNG in order to be compatible with receive_meteor.sh script. I've also changed satellite height to 830 km since according to https://www.n2yo.com/satellite/?s=40069 perigee is 826.8 km, and apogee is 833.6 km as of 14 October 2020.

I've experienced issue when I put in +2 timezone, the script calculates sun elevation for -2 timezone so i changed plus to minus in time.localtime function. Also added support for Daylight saving time.