Remove unuseful statement, it does nothing
Improve usability of increase new/review card limit dialog

*Show to the user the number of card left in the deck exceeding the ones under review
*Fix spin box max value accordingly
Update deck schema to support new/review card limit reset

TODO: This update in the schema should be done in the storage.py module
Add reset new/review card limit buttons

In the custom study dialog, two buttons has been added to reset the effect of increase new card/review due limit for today.