ensure `hexplt2ppm.sh` works with hexplt format files that have comments

[earthbound19]

use this updated code from renderHexPalette.sh that gets all hex codes whatever else is around them:

get array of colors from file by extracting all matches of a pattern of six hex digits preceded by a #:

colorsArray=( $(grep -i -o '#[0-9a-f]{6}' $hexColorSrcFullPath | tr -d '#') ) # tr command removes pound symbol, and surrounding () makes it an actual array

Get number of colors (from array):

numColors=${#colorsArray[@]}