There is also my program HARMONY, although I wouldn't describe it as full notation software, as I haven't yet incorporated all the symbols that might be needed. Call it 'draft-mode' perhaps, but suitable for folk song.

But it DOES have the following features

Imports most abc tunes
Displays lyrics, including multiple verses of aligned lyrics
Automatically adds beams (between quavers, semiquavers etc)
Writes and plays back tunes as MIDI files
Adds chords to a melody (This was the original purpose of the program)
Adds accompaniment notes/voices based on the chords, in various styles

Now has drag and drop of notes for editing
Automatically generates new tunes in specified styles

Can include effects such as bend, pan, volume change, modulation (tremelo/vibrato) by 'note styles'

IMPORTANT
If you want to try it, please do NOT download until version 3.3.7 is available, which should be by Monday (24th Jan).

The current download, 3.3.6, does work, but has a few bugs in the drag and drop facility.

My site where you can see some examples of the output by moving the mouse over the navigation links on the main page.