Cppcheck found some issues. Solved some of them.

- Member variables `ControlDoublePrivate::m_trackType` and
`ControlDoublePrivate::m_trackFlags` was not initialized in the
constructor.
 - `SoundSourceProxy::ParseHeader`: return `OK` instead of `0`.
 - `TrackInfoObject::parse`: omitted implicit cast.
 - `TrackCollection`: added references to arguments in methods
`getTrackSource...`
 - `chromaprinter.cpp`: Memory leak: `pData` (return without freeing
`pData`).
 - In `GLSLWaveformRendererSignal::createFrameBuffers` was strange
expression: `m_framebuffer->isValid() && m_framebuffer->isValid()`.
 - Lots of postfix ++/-- changed to prefix form.