Added Dance Mat support for the Family Trainer/Active Life series.

Select the dance mat via Configure > Gamecube > Port 1 > Dance Mat

The dance mat is mapped to the GC Pad:

D-Pad Up = Blue Arrow Up
D-Pad Down = Blue Arrow Down
D-Pad Left = Blue Arrow Left
D-Pad Right = Blue Square
Y Button = Orange Arrow Up
A Button = Orange Arrow Down
X Button = Orange Arrow Right
B Button = Oranage Square

Source/Core/Core/Core.vcxproj

@@ -298,6 +298,7 @@
     <ClCompile Include="Src\HW\SI.cpp" />
     <ClCompile Include="Src\HW\SI_Device.cpp" />
     <ClCompile Include="Src\HW\SI_DeviceAMBaseboard.cpp" />
+    <ClCompile Include="Src\HW\SI_DeviceDanceMat.cpp" />
     <ClCompile Include="Src\HW\SI_DeviceGBA.cpp" />
     <ClCompile Include="Src\HW\SI_DeviceGCController.cpp" />
     <ClCompile Include="Src\HW\SI_DeviceGCSteeringWheel.cpp" />
@@ -498,6 +499,7 @@
     <ClInclude Include="Src\HW\SI.h" />
     <ClInclude Include="Src\HW\SI_Device.h" />
     <ClInclude Include="Src\HW\SI_DeviceAMBaseboard.h" />
+    <ClInclude Include="Src\HW\SI_DeviceDanceMat.h" />
     <ClInclude Include="Src\HW\SI_DeviceGBA.h" />
     <ClInclude Include="Src\HW\SI_DeviceGCController.h" />
     <ClInclude Include="Src\HW\SI_DeviceGCSteeringWheel.h" />