Use RUBY_ENGINE instead of RUBY_PLATFORM to detect JRuby.
config/{lingo,lir}.cfg: Binding for eval does know +cmd+ again. (0189724, 72024c6)
lib/lingo/attendee.rb: Every attendee can init, control and process.

Also, simplify skip command logic.
lib/lingo/attendee/{debugger,vector_filter}.rb: Initialize instance variables.
lib/lingo/attendee/: Make init, control and process public.
lib/lingo/attendee.rb: Make forward and command public, dropping accept and listen.
lib/lingo/attendee.rb: Make subscribers public.
lib/lingo/attendee/text_reader.rb (control): Skip TALK command.
lib/lingo/attendee/text_reader.rb (control): Signify end of processing.
lib/lingo/deferred_attendee.rb: New attendee that defers all forwarding until end of processing.
test/ref/lir.ve{n,r}: Added reference files.
lib/: Use Hash.seen from nuggets.
lib/: Use Hash.nest from nuggets.
ChangeLog: Updated with recent changes.
lib/lingo/attendee/vector_filter.rb: Added support for TFIDF scoring.