Don't accidentally compile miniz as a separate C file

--HG--
rename : miniz.c => miniz.h
Make sure the framework version matches the version of the dylib built from command line.
Updated Visual Studio project
Use OutDir, which is correct for all configurations and all platforms.
Added the external directory to the release archive
Make sure the .m files come from the source directory
Run an update loop to refresh the display if the window is obscured for some reason.
This fixes black screen on Linux in VMware
Improved find_lib, gets the latest version of libpng, etc.
Updated configure
Fix VS compiler warnings
Fix VS 2010 and 2012 projects for showimage