fix wrong Row number in DiscoveryDialog.py that caused following traceback:

Traceback (most recent call last):
File "/home/beremiz/beremiz/ProjectController.py", line 1536, in _Connect
dialog = DiscoveryDialog(self.AppFrame)
File "/home/beremiz/beremiz/dialogs/DiscoveryDialog.py", line 124, in __init__
self._init_ctrls(parent)
File "/home/beremiz/beremiz/dialogs/DiscoveryDialog.py", line 121, in _init_ctrls
self._init_sizers()
File "/home/beremiz/beremiz/dialogs/DiscoveryDialog.py", line 73, in _init_sizers
self._init_coll_ButtonGridSizer_Growables(self.ButtonGridSizer)
File "/home/beremiz/beremiz/dialogs/DiscoveryDialog.py", line 64, in _init_coll_ButtonGridSizer_Growables
parent.AddGrowableRow(1)
File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk2/wx/_core.py", line 15343, in AddGrowableRow
return _core_.FlexGridSizer_AddGrowableRow(*args, **kwargs)
PyAssertionError: C++ assertion "!m_rows || idx < (size_t)m_rows" failed at ../src/common/sizer.cpp(1967) in AddGrowableRow(): invalid row index

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<PyFile>
  <variables/>
  <globals>
<![CDATA[
from threading import Thread

def OnConnectButton(self, event):
  def OnWiiConnected(mac_addr):
    self.label_2.SetLabel(
      "Wiimote %s connected"%mac_addr 
      if mac_addr else 
      "Wiimote connection failed !")

  def WiiConnected(mac_addr):
    wx.CallAfter(OnWiiConnected,mac_addr)

  Thread(target = Connect_Wiimote, args = (WiiConnected,)).start()
  self.label_2.SetLabel("Press wiimote 1+2")
  event.Skip()

def OnDisconnectButton(self, event):
  Disconnect_Wiimote()
  self.label_2.SetLabel("Wiimote disconnected")
  event.Skip()

]]>
  </globals>
  <init>
<![CDATA[
]]>
  </init>
  <cleanup>
<![CDATA[
]]>
  </cleanup>
  <start>
<![CDATA[
]]>
  </start>
  <stop>
<![CDATA[
]]>
  </stop>
</PyFile>