snow dissappears at border of window in bin/term_snow

[fwolfst]

❄️ besides the disappointing not-covering snow at the bottom of the screen, probably there is an error in https://github.com/flori/term-ansicolor/blob/678eaee3e72bf51a02385fa27890e88175670dc0/bin/term_snow#L54 (I guess it should read += not ==). I cannot simulate the consequences atm.