[imp] pdf image preview

[Liam Hoekenga]

> I'm pretty sure that my imagemagick installation is working.  ldd doesn't 
> show any missing libraries, and phpinfo() shows that the imagick extension is 
> loaded.
>
> What am I missing?

ghostscript.  Following an strace..

     12195 write(2, "sh: gs: command not found\n", 26) = 26

Apparently, it uses ghostscript and imagemagick are needed to make png 
thumbnails from pdf files.  This should probably be documented.

Liam