Add support for template NSImages to wxBitmap

wxBitmap uses CGImage instead of NSImage internally and the conversion
looses NSImage metadata.  In particular, it looses the "template"
attribute, which is set for files ending with "Template" and loaded
trough wxArtProvider.

This change makes it easy to use template images with native controls
such as the toolbar.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78016 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Merge branch 'master' of ../wxWidgets_vanilla_trunk-svn into merge
sync with upstream (SVN); patched for ICC; removed files we do not support

Signed-off-by: Marian 'VooDooMan' Meravy <vdm113@gmail.com>
restore our project files

Signed-off-by: Marian 'VooDooMan' Meravy <vdm113@gmail.com>
restore our git files

Signed-off-by: Marian 'VooDooMan' Meravy <vdm113@gmail.com>