Installing JPEGTRAN with drop support on a Mac

JPEGTRAN is needed for jpeg optimizations, especially if you like to do some web scraping and
the images are only accessible behind zoomify. But this is something for another post.

Installation 

1. Get the source code from here: http://www.ijg.org/
2. Download jpegsrc.v9a.tar.gz
3. Get the patch from here: http://jpegclub.org/jpegtran/
4. Download droppatch.v9a.tar.gz
5. Uncompress the package, i.e. tar -xzvf /tmp/jpegsrc.v9a.tar.gz
6. Uncompress the patch to the same directory as jpegtran, i.e. 
   tar -C jpeg-9a -xzvf droppatch.v9a.tar.gz 
7. Go to the directory that contains the uncompressed original code with the patch, i.e 
   cd /tmp/jpeg-9a
8. if you don't want to install it to the default locations, add the --prefix arg otherwise without, ./configure --prefix=/some/installation/path/ 
9. make && make install (you need sudo for installation to default path)

Done!