A couple of changes:
* The bar now measures progress instead of % correct. TODO change the names of the elementIds to reflect this (perhaps "bar_background" and "bar")
* Incorrect entries are added to the back of the active vocab list. You now must answer them all correct to finish successfully.
* cmake now installs the themes...
* New design: the logic classes (Statistics, PracticeEntryManager, AnswerValidator, Hint) can now keep pointers to each other (since they will exist in every
mode); however, the other gui, ui, etc classes will still be in the void, since they are optional and volatile.
* Update of TODO