new activities:
* calendar
* find the date
* family
* family find relative
* memory case association
* memory case association with Tux
* submarine
* electricity
misc:
* Add Tutorial item to be able to have activity introductions with both images and texts (some activities can be updated to use it)
* Add easy mode in letter in word with less words displayed
* Add license page
todo:
* ~~finish family new graphics~~ - done
* ~~finish submarine new graphics~~ - done
* ~~finish calendar/find_the_date new graphics~~ -done
* ~~finish digital_electricity new graphics~~ -done
* fix submarine controls and tuto layout on tablet screens
* ~~style chess coordinates~~ -done
* ~~add changelog in the code~~
* ~~finding a more visible solution to tell the user he can scroll on the menu (the fade not being visible with software renderer).~~ added GCScrollButtons for NoOpenGL
* ~~No light in Tux's house in renewable_energy~~ (https://github.com/gcompris/GCompris-qt/issues/212)
* https://github.com/gcompris/GCompris-qt/issues/213: see what can be added
* check if minimalizing the code before release is useful ("find -type f -name \*qml -exec qmlmin {} ;" minus ActivityInfo.qml), seems to win 300ko for the apk, worth it?
* ~~do a first beta to look for bugs~~, then string freeze, followed by news for release
* remove penalty voices because we need to click on the goal instead of the ball.