erroneously squashed commit.

add skeleton of the viewer program.
cleanup: un-export the clipping function (they are private).
add a function to calculate the centroid of an object.
cleanup stale linking directory
cleanup stale linking directory /2
build eonview
reorganize the code and the option handling.
screenshot enhancements.

- more image format support (PNG, BMP).
- meaningful screenshot names.
Merge branch 'eonview'
port to the new console API.