Update Timezone to be Timezone Offset

Update semantics of what the "timezone" parameter actually is in this
context to make room for the actual timezone configuration.

install.sh

@@ -262,13 +262,15 @@ read -rp "Enter your latitude (South values are negative): "
 read -rp "Enter your longitude (West values are negative): "
     lon=$REPLY
 
-read -rp "Enter your timezone (Ex: -3 for Argentina time): "
-        timezone=$REPLY
+# note: this can probably be improved by calculating this
+# automatically - good for a future iteration
+read -rp "Enter your timezone offset (ex: -3 for Argentina time): "
+    tzoffset=$REPLY
 
 sed -i -e "s/change_latitude/${lat}/g;s/change_longitude/${lon}/g" "$HOME/.noaa.conf"
 sed -i -e "s/change_latitude/${lat}/g;s/change_longitude/${lon}/g" "$HOME/.wxtoimgrc"
 sed -i -e "s/change_latitude/${lat}/g;s/change_longitude/$(echo  "$lon * -1" | bc)/g" "$HOME/.predict/predict.qth"
-sed -i -e "s/change_latitude/${lat}/g;s/change_longitude/${lon}/g;s/change_tz/$(echo  "$timezone * -1" | bc)/g" "sun.py"
+sed -i -e "s/change_latitude/${lat}/g;s/change_longitude/${lon}/g;s/change_tz/$(echo  "$tzoffset * -1" | bc)/g" "sun.py"
 
 success "Install done! Double check your $HOME/.noaa.conf settings"