Keyword filtering that doesn't depend on input buffer size and the way input lines got split between filter() calls. KewordFilter got state to keep processed suspicious ...$ lines

[section1]
# comment
key1=value 1
key2=value 2
key3=value 3#comment

%include ./included.rc

[section3]
key1=value 1-3

[section1]
key4=value 4
%unset key1