Fix minor voice bugs

[YunusAndreasson]

• [x] Stop button does not switch to Play when finished playing sound
• [x] Word is not played when pressing it in practice
• [x] A last word is played after "Takbir"
• [x] Buttons should be moved down when sentence practice is finished
• [x] Stop audio when pressing continue or leaving the screen in sentence practice
• [ ] Should not be possible to play two sounds and the same time