Introduce Speed instead of Pitch/Rate, to match other place in Mixxx and Manual
https://bugs.launchpad.net/mixxx/+bug/1283190
User Speed term for combined Pitch/Tempo control in ControlPickerMenu
Fix some var names and comments to Speed = Pitch / Tempo
removed unused getPitchIndpTimeStretch()
Playback Speed without Slider
Increase/Decrease Speed
replace pitch-bend with Temporary Increase/Decrease Speed
Add a (Vinyl "Pitch" slider) hint
Temporary -> Temporarily Up -> faster down -> slower
Improved tooltip of the Speed Range combobox
Added Adjustment to the group box headers
Removed key and tempo related parts of speed tooltip, Edded space before %
Merge pull request #409 from daschuer/speed_rename

Speed rename
Reverted ugly space-before-percent thing.
LateNight: disable master sync debug helper widgets for release
Deere: replace funny colors with goofy gradients.
Fix typo
Update translation template. Found 1856 source text(s) (39 new and 1817 already existing). Kept 33 obsolete entries
Delete obsolete include directives
New SoundSource/AudioSource API

This is the first step towards a better/cleaner SoundSource API.
The operations for reading audio data have been moved into the
new abstract base class AudioSource.

Currently SoundSource inherits from AudioSource for technical reasons.
This is too much much coupling that needs to be broken up. I have
already some ideas on how to resolve it, but first this work needs to
be integrated.

During the refactoring I've noticed, that the quality and maturity of the
audio decoders for different file types greatly varies:

Good/mature:
- FLAC
- Ogg
- Opus
- WavPack
- libsndfile

Mediocre:
- MP3

Ugly/inefficient:
- M4A
- ModPlug

Untested AudioSource API:
- Apple CoreAudio
- Windows Media Foundation

Unfinished AudioSource API (just a hack):
- FFmpeg

Especially the code for the M4A decoder should be revised and cleaned up as
soon as possible, followed by a review of the MP3 decoder. Reading audio
data must work as stable and efficient as possible. This has priority over
the improvement of the internal software architecture!