Create a copy of the sdi project without an image list set to 3.1 code generation.

[Randalphwa]

Description:

Create a copy of sdi called sdi_31 which does not have an Image List file and is set to generate 3.1 compatible code. This would provide testing for the more common scenario of no Image List file, while at the same time verifying that code generation for wxWidgets 3.1 is working correctly.

Note that CMake should be able to switch between wxWidgets31, wxWidgets32 and wxWidgets33 and the code should still work fine since the 3.1 setting just adds conditionals that provide both 3.1 and 3.2 comparability.