Fix planegame (report changes on Score.qml).
AudioFilePath for voices files depending on locale.
algebra_by, major rework

- improved images based on openclipart.org
- improved animation
- simplified code
core, minor added transparency on buttons.
added memory-math-add-minus-mult-div

Improved dataset for memory-math-div, memory-math-mult-div,
memory-math-mult.

Made Sound a common item instead of being on each card.
memory, cleanup removed useless files.
 Merge branch 'master' into 'master'

Fix planegame (problems with latest score.qml) + audio files