fix backtrace on opening program/resource on small screens

Fix regression introduced by f4696d8 ("add stretching to columns Name,
Type, Doc in variable panel").
This problem happens only on wxPython-3.0.

show whether instance of SFC action is currently active or not in its
debug instance view

clean PLC log only if there is something to clean

Otherwise exception happens in Beremiz service.

Traceback (most recent call last):
File "/home/developer/WorkData/PLC/beremiz/beremiz/connectors/PYRO/_init_.py", line 113, in catcher_func
return func(*args, **kwargs)
File "/home/developer/WorkData/PLC/beremiz/beremiz/connectors/PYRO/_init_.py", line 194, in my_local_func
return RemotePLCObjectProxy._getattr_(attrName)(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/Pyro/core.py", line 381, in _call_
return self._send(self._name, args, kwargs)
File "/usr/lib/python2.7/dist-packages/Pyro/core.py", line 456, in _invokePYRO
return self.adapter.remoteInvocation(name, Pyro.constants.RIF_VarargsAndKeywords, vargs, kargs)
File "/usr/lib/python2.7/dist-packages/Pyro/protocol.py", line 457, in remoteInvocation
return self._remoteInvocation(method, flags, *args)
File "/usr/lib/python2.7/dist-packages/Pyro/protocol.py", line 532, in _remoteInvocation
answer.raiseEx()
File "/usr/lib/python2.7/dist-packages/Pyro/errors.py", line 72, in raiseEx
raise self.excObj
AttributeError: 'PLCObject' object has no attribute '_ResetLogCount'
+--- This exception occured remotely (Pyro) - Remote traceback:
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/Pyro/protocol.py", line 719, in _handleInvocation2
res = obj.Pyro_dyncall(req[1],flags,req[3]) # (method,flags,args)
File "/usr/lib/python2.7/dist-packages/Pyro/core.py", line 108, in Pyro_dyncall
return getattr(self.delegate or self,method) (args,*keywords)
File "/home/developer/WorkData/PLC/beremiz/beremiz/runtime/PLCObject.py", line 101, in ResetLogCount
if self._ResetLogCount is not None:
AttributeError: 'PLCObject' object has no attribute '_ResetLogCount'
+--- End of remote traceback

reset loaded messages counts on new PLC program trasnfer

This fixes the problem that first message from newer PLC program maybe
lost, if it's issued before first PLC log fetching.

Closes #23

add function block to variable panel if fb is added using toolbar

Closes #25

enable to write SFC transition in IL

This commit reverts previous commit 3f3d97be9a9f.
Because the fix for the matiec problem is already upstream
(https://bitbucket.org/mjsousa/matiec/commits/ce026aee03e00c0790948a18bd7b35805457da81)

fix debug button and variable tree generate for actions and transitions in POU instance variable panel
for 'None' type instances(Python POU's, Native, SVGUI, user-defined pou's, etc.) debug button will be disabled. If action or transition instances have opened in instance variable panel,variables from main POU will be loaded. When user press debug button on variable instance in action or transition, instance path to main POU will be used, because all variables of action or transition in instance variable tree belong to main POU.

clear variable location cell in variable panel, if variable class or type changed
if variable class is not local or global, or variable type is not locatable, variable location cell would be empty and read-only

runtime is licensed under LGPLv2.1

make command line help message for Beremiz more verbose