Switch from QMediaPlayer to QSoundEffect for notification sound

[danfe]

In 5c5a5b0, notification sound had been improved by making its volume configurable (and setting it to 50% by default). Previously, the notification sound was indeed a bit too loud. :-)

However, please consider using QSoundEffect class instead, as QMediaPlayer does not work if Qt5 multimedia package was built without GStreamer support, complaining to the console:

defaultServiceProvider::requestService(): no service found for - "org.qt-project.qt.mediaplayer"

While QSound and QSoundEffect classes work with just core sound backend like ALSA or OSS.

The patch is ready and tested.

[martinrotter]

Fixed RN. :)

94585e5

[danfe]

I think you've missed one thing upon merging my patch: when using QSoundEffect API, its setVolume() method (called on line 60 of librssguard/miscellaneous/notification.cpp) takes real argument, not integer. My code used static_cast<qreal>(m_volume) / 100, your similar code below uses implicit type promotion as (m_volume * 1.0f) / 100.0f, but either way, currently *.wav notification sounds play at full volume.