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

     1

#Encoding of BACnet Object Types;;;

     2

#Code;Object Type;;

     3

0;Analog Input;;

     4

1;Analog Output;;

     5

2;Analog Value;;

     6

3;Binary Input ;;

     7

4;Binary Output;;

     8

5;Binary Value;;

     9

6;Calendar;;

    10

7;Command;;

    11

8;Device;;

    12

9;Event-Enrollment;;

    13

10;File;;

    14

11;Group;;

    15

12;Loop;;

    16

13;Multistate Input;;

    17

14;Multistate Output

    18

15;Notification Class

    19

16;Program

    20

17;Schedule

    21

18;Averaging

    22

19;Multistate Value

    23

20;Trend Log

    24

21;Life Safety Point

    25

22;Life Safety Zone

    26

23;Accumulator

    27

24;Pulse Converter