Separation of IDVI code and non-IDVI code

1. Classes specific to IDVI are placed in a package inside the package "idvi".

   This includes pk font file and dvi file processing code in the packages "idvi.io", "idvi.font", and "idvi.dvi", and IDVI user interface and dvi processing code in the packages "idvi.controls", "idvi.display", and "idvi.split".

2. Classes believed to be of general interest are placed in top level packages of their own.

   This includes generic parameter processing classes in "parameter", html tag parsing classes in "html", and lock and condition variable classes in "util".