Fix premature truncation of brief descriptions in Doxygen comments.

Don't end the brief description at the first period if it's a period which is
part of "i.e." or "e.g.": escape the space following it to prevent Doxygen
from recognizing it as an end of sentence.

See #14866.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73084 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/image.h

@@ -1356,7 +1356,7 @@ public:
     bool IsOk() const;
 
     /**
-        Returns @true if the given pixel is transparent, i.e. either has the mask
+        Returns @true if the given pixel is transparent, i.e.\ either has the mask
         colour if this image has a mask or if this image has alpha channel and alpha
         value of this pixel is strictly less than @a threshold.
     */