Fixes for date number

[garrettjstevens]

Fixes #1

• The date formats %j and %H return 0-padded numbers, for example "001" for Jan. 1 or "09" for 9 am. Bash arithmetic interprets numbers that start with a 0 as octal numbers, though, which can lead to unexpected results. For example, $((024)) evaluates to 20, and $((09)) throws an error since that is not a valid octal number. Adding the 10# here forces it to evaluate it as a base 10 number, which should give the expected results.
• Adds --utc to the date calls so that you get the same result no matter your local timezone (and it should match what the Dial-A-Moon expects more accurately).
• Uses the stored $num to create the $im variable so it doesn't have to get calculated again.

This is a fun idea for a desktop background, thanks for making it!

[desertplant]

Thank you very much! These are great fixes that should fix the issue one user had.

[MAlfare]

2023 is not so far away. This is what I have done. I hope it will work ;-) 2023-age.txt 2023-phase.txt Adjustments for 2023.txt

[desertplant]

thanks again MAlfare!