Access to "clean" solution tree

[d4tocchini]

• remove unnamed paths / anonymous promises
• collapse continuations into nearest parent tree

[cbchouinard]

I second :) This would be super useful. Could it be useful to know from which node in the path the child path comes from:

solutionTree =
path: [ 'root', 'contest_multiply', 'middle', 'contest_division', 'end' ]
children: [
path: ['contest_multiply', ['a','3', 'tripled']]
path: ['contest_division', ['b', '5', 'half']]
]

[bergie]

This is what Choice.toSong() should do, but there seems to be some issue with getting the children right. Needs to be fixed.