Migrate Problems Database to PreTeXt Version

[bmontana]

The database of problems that can be assigned in the PreTeXt (ptx) version started out almost empty, except for in-chapter problems. The Restructured Text (rst) version has a huge number of user-contributed problems. I have used these for coding assignments.

I would like for the rst problems to be migrated over to the ptx version.

I have been duplicating the problems I used in the rst version for use in the ptx version. I have changed the activecode uniqueid by adding '_c' (for 'copy') to the end so that these ids don't conflict with those in the database, should you port them over at some point.

I'm not sure if Feature Requests is the correct place for this. But it's not a bug, either.