* fix: handle the sorting of transformed files
We can't use the ext property, since that is transformed, but the
history is maintained.
* test: make solutions polyVinyls for sorting
* refactor: inline prepareChallenge
* refactor: make solutions polys in getChallenges
* fix: convert each solution to a poly
* fix: skip empty solutions
* fix: get challenge file history in client
* refactor: stop calling isPoly from the client
* fix: remove debug console.log
* refactor: remove unnecessary sorting step