py_ext: fix CSV Writer

fix POU logic :
- SAVE is a BOOL
- invocation of py_eval on rising edge of SAVE
- remove save python argument

fix python:
- use no encoding for file open (python2)
- re-use detected dialect if any
- use no "rt+" and truncate since no need to re-sniff dialect for output file
- return "OK" instead of "#SUCCESS", preventing POU logic to ACK result
- support creating new line if writing just after last line
- support appending data on short rows

fix example:
- use a HMI:Button to trigger CSV write instead of HMI:Input +1
- reload CSVs on on each new CSV opened in file browser
- add display of CSV write output

#!/bin/bash

INKSCAPE=inkscape

for i in `cat icons.svg |grep -o -e '%%[^%]*%%'|sed 's/%//g'` 
do
 if [ $i.png -nt icons.svg ]; then
 	echo "Skip $i"
 else
	rm  -f $i.png
	echo "$INKSCAPE" icons.svg -z -e $i.png -i $i
	"$INKSCAPE" icons.svg -z -e $i.png -i $i
 fi
done