fix issue with sometimes wrong return code of ProcessLogger


As a result of wrong return code Beremiz gives folowing traceback:
Traceback (most recent call last):
File "./Beremiz.py", line 850, in OnMenu
getattr(self.CTR, method)()
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 925, in _Build
IECGenRes = self._Generate_SoftPLC()
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 568, in _Generate_SoftPLC
return self._Compile_ST_to_SoftPLC()
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 661, in _Compile_ST_to_SoftPLC
C_files.remove("POUS.c")
ValueError: list.remove(x): x not in list

The problem is that both threads (for reading stdout and stderr) call self.Proc.poll(),
that updates internal returncode field. This call is done without any locking and the first thread gets correct result,
but other gets 0 as retval. If 0 gets thread, that afterwards calls callback finish, then wrong return code is returned
to the parent. Now only the thread with a callback polls for the return code, other thread just checked local value.

Additionally function spin() waits now until all threads finish reading their pipes, so the results are always correct.

     1

Beremiz installation 

     2

====================

     3

     4

Windows

     5

-------

     6

Download installer, install. 

     7

     8

Linux

     9

-----

    10

Pre-requisites::

    11

    12

    # Ubuntu/Debian :

    13

    sudo apt-get install python-wxgtk2.8 pyro mercurial

    14

    sudo apt-get install build-essential bison flex python-numpy python-nevow

    15

    16

Prepare::

    17

    18

    mkdir ~/Beremiz

    19

    cd ~/Beremiz

    20

    21

Get Source Code::

    22

    23

    cd ~/Beremiz

    24

    25

    hg clone http://dev.automforge.net/beremiz

    26

    hg clone http://dev.automforge.net/plcopeneditor

    27

    hg clone http://dev.automforge.net/matiec

    28

    29

Build MatIEC compiler::

    30

    31

    cd ~/Beremiz/matiec

    32

    ./configure

    33

    make

    34

    35

Build CanFestival (optional):: 

    36

    37

    # Only needed for CANopen support. Please read CanFestival 

    38

    # manual to choose CAN interface other than 'virtual'::

    39

    40

    cd ~/Beremiz

    41

    hg clone http://dev.automforge.net/CanFestival-3

    42

    43

    cd ~/Beremiz/CanFestival-3

    44

    ./configure --can=virtual

    45

    make

    46

    47

Launch Beremiz::

    48

    49

    cd ~/Beremiz/beremiz

    50

    python Beremiz.py

    51