Build by default with optimization level -O2 for GCC

before -O0 was used by default, that caused pretty bad performance.

Amd64, i6700k, 4200MHz, GNU/Linux (non-RT kernel), gcc 7.2.0

-------------------------------------
Optimization | EN/ENO |no EN/ENO |
-------------------------------------
default | 11 | 9.5 |
-O3 | 3.9 | 5.2 |
-O2 | 4 | 4.8 |
-Os | 4.1 | 3.5 |
-Ofast | 3.9 | 5.2 |
-------------------------------------

ARM, BBB Cortex-A8, 600Mhz, GNU/Linux, gcc 4.6.3

-------------------------------------
Optimization | EN/ENO |no EN/ENO |
-------------------------------------
default | 273 | 226 |
-O3 | 141.8 | 106.2 |
-O2 | 142 | 107 |
-Os | 152.5 | 112.2 |
-Ofast | 141.7 | 106.2 |
-------------------------------------

For embedded systems with size constaints (like Cortex-Mx, AVR and so
on) I usually use -Os. It gets pretty good results. For
GNU/Linux-based systems -O2 is usually a good choice, as you see the
test results.

<?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>