Applied patch to add n bitmaps at once to an image

  Applied patch to add n bitmaps at once to an image
    list of the bitmap is n times as wide as the
    image width of the image list. This was the case
    in the MSW image list before.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@38965 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775