Fix leak of imagemagick blob when writing to a memory block.  https://tracker.physiomeproject.org/show_bug.cgi?id=2378   Merged from cmgui6735_pluspatch revision 6798.
Fix leak of imagemagick blob when writing to a memory block. 
https://tracker.physiomeproject.org/show_bug.cgi?id=2378  
Merged from cmgui6735_pluspatch revision 6798.


git-svn-id: 4705079bc6b8aadf675e3696f5c015a6aa4916e3@6975 3c1deb5b-d424-0410-962d-aba41a686d42

OpenCMISS/zinc,OpenCMISS/zinc,hsorby/zinc,OpenCMISS/zinc,OpenCMISS/zinc,hsorby/zinc,hsorby/zinc,hsorby/zinc