New levels set for algebra additions and subtraction

[LittleWhite-tb]

Hello,

This pull request adds new levels for additions/subtraction activities (algebra_plus/algebra_minus). Three levels are added:

• random operations with operands between 0 and 10
• random operations with operands between 0 and 15
• random operations where the result is between 0 and 100 I made this in order to complete the set of levels in this activities (the actual set is based on operations table from 0 to 10).

The PR also brings some refactoring (impacts algebra_by/algebra_divide/algebra_minus/algebra_plus):

• the 11th level was implicit in the code (no level Data.qml for it). It generated 5 sublevels from previous level. Now, the 11th has its "special" Data.qml that constraints the operation generation.

And also small fixes:

• bonus appears on top of score
• sublevel counter is not increased when the level is finished

[allon49]

Hi, Excellent work! It adds something I always wanted in algebra. Do you want to add the addition mecanisms to the other operators before we merge? If you wish to contribute more I can help you accessing to our official gitlab tool. Thanks for your work! Emmanuel

[LittleWhite-tb]

This PR is now a merge request on official KDE infrastructure: https://invent.kde.org/education/gcompris/-/merge_requests/150 Let's continue discussion there :).