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.