WIP: made a CopyBuffer class, so that we could (later) save history

	modified:   editor.rb
WIP: saving copy history, in theory

	modified:   editor.rb
WIP: trying to get paste menu to work

	modified:   editor.rb
copy buffer history seems to be working

	modified:   editor.rb
copybuffer menu: show in reverse chronological order

	modified:   editor.rb