Reimplementation of prefix sets.
Prefix sets were broken beyond any repair and have to be reimplemented.They are reimplemented using a trie with bitmasks in nodes.There is also change in the interpretation of minus prefix pattern,but the old interpretation was already inconsistent with...
Even better documentation of filters.
Better progdocs for filters
do not overflow in .dvi
include filter documentation in the system
Added skeleton Doc files for the whole developer's documentation.