Possible fix for bug #435

I say possible because I can't fully test it as my motherboard
audio device doesn't show up in Windows (don't know why yet).

So, because of that and because this "fix" needs a little discussion
amongst the troops, I've ifdef'd it with EXPERIMENTAL_HAVE_DEVICE_CHANGE
and have disabled it by default.

What is does is it sets up a device change listener and performs an
automatic rescan when a change is detected.  (That's the part that
needs discussion.)

win/Projects/Audacity/Audacity.vcxproj

@@ -244,6 +244,7 @@
     <ClCompile Include="..\..\..\src\CaptureEvents.cpp" />
     <ClCompile Include="..\..\..\src\commands\OpenSaveCommands.cpp" />
     <ClCompile Include="..\..\..\src\Dependencies.cpp" />
+    <ClCompile Include="..\..\..\src\DeviceChange.cpp" />
     <ClCompile Include="..\..\..\src\DeviceManager.cpp" />
     <ClCompile Include="..\..\..\src\DirManager.cpp" />
     <ClCompile Include="..\..\..\src\Dither.cpp" />
@@ -519,6 +520,7 @@
     <ClInclude Include="..\..\..\src\BlockFile.h" />
     <ClInclude Include="..\..\..\src\CaptureEvents.h" />
     <ClInclude Include="..\..\..\src\commands\OpenSaveCommands.h" />
+    <ClInclude Include="..\..\..\src\DeviceChange.h" />
     <ClInclude Include="..\..\..\src\effects\EffectRack.h" />
     <ClInclude Include="..\..\..\src\effects\NoiseReduction.h" />
     <ClInclude Include="..\..\..\src\effects\Phaser.h" />