Testing each element of the public API

# Constructor

- [x] `audioElement` throwing exceptions
- [ ] options
- [ ] `waveformOverviewReady`

# Segments

- [x] `addSegment`
- [x] `getSegments`

# Time

- [x] `getCurrentTime`

# Zoom

- [x] `zoomIn`
- [x] `zoomOut`
- [x] `setZoom`
- [x] `getZoom`