Load images for EtherCAT extension

Fixes following backtrace:

Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk3/wx/_core.py", line 16765, in <lambda>
lambda event: event.callable(*event.args, **event.kw) )
File "/home/developer/WorkData/PLC/beremiz/beremiz/BeremizIDE.py", line 1074, in AddConfNode
self._Refresh(TITLE, FILEMENU, PROJECTTREE)
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 917, in _Refresh
self.RefreshFunctions[element]()
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1526, in RefreshProjectTree
self.GenerateProjectTreeBranch(root, infos)
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1565, in GenerateProjectTreeBranch
self.GenerateProjectTreeBranch(item, values)
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1554, in GenerateProjectTreeBranch
self.TreeImageDict[icon_name] = self.TreeImageList.Add(GetBitmap(icon_name))
File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk3/wx/_gdi.py", line 6735, in Add
return _gdi_.ImageList_Add(*args, **kwargs)
ValueError: invalid null reference in method 'ImageList_Add', expected argument 2 of type 'wxBitmap const &

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# See COPYING.Runtime file for copyrights details.
#

from __future__ import absolute_import
from ctypes import CDLL, RTLD_GLOBAL, pointer, c_int, POINTER, c_char, create_string_buffer


def TryPreloadXenomai():
    """
    Xenomai 3 (at least for version <= 3.0.6) do not handle properly dlclose
    of shared objects whose dlopen did trigger xenomai_init.
    As a workaround, this pre-loads xenomai libraries that need to be
    initialized and call xenomai_init once for all.

    Xenomai auto init of libs MUST be disabled (see --auto-init-solib in xeno-config)
    """
    try:
        for name in ["cobalt", "modechk", "copperplate", "alchemy"]:
            globals()[name] = CDLL("lib"+name+".so", mode=RTLD_GLOBAL)
        cobalt.xenomai_init(pointer(c_int(0)), pointer((POINTER(c_char)*2)(create_string_buffer("prog_name"), None)))
    except Exception:
        pass