[nondet]pack_property(?Pack, 
?Property)True when Property is a property of an installed Pack. 
This interface is intended for programs that wish to interact with the 
package manager. Defined properties are:
- directory(Directory)
 - Directory into which the package is installed
 
- version(Version)
 - Installed version
 
- title(Title)
 - Full title of the package
 
- author(Author)
 - Registered author
 
- download(URL)
 - Official download URL
 
- readme(File)
 - Package 
README file (if present) 
- todo(File)
 - Package 
TODO file (if present)