Purely cosmetic cleanups to VinylControl / VinylControlXwax.

* Delete dead code.

* Initialize all variables.

* Clarify some variable names.

* Move member-variables to local when used purely as locals.

* Comment a lot of the member variables.
Remove dead code.
Rename remaining non-m_-prefixed variables.
Attack of the style police.
Remove redundant checkmark icon in Preferences > Skin drop-down menu. Only displays warning icon, if the minimum size of the selected skin is bigger than the screen resolution.
Change wording for warning message, that is displayed below the skin drop-down-menu, if the minimum size of the selected skin is bigger than the screen resolution. Reflects that we have resizable skins now.
Update warning icon displayed in the Skin selection drop-down menu.
Add warning icon to the icon template
Provide better error message if we fail to save a recording.
Merge pull request #130 from esbrandt/lp1081132

Remove redundant icon in Preferences > Interface > Skin drop-down menu
Wording
Merge pull request #131 from esbrandt/error-message-recordings

Provide better error message if we fail to save a recording.
Refactor EngineBufferScale::getScaled API to be a little more clear.

* Get rid of the split between rate and tempo -- just represent it as speed.
* Split baserate out of rate.
* Add a boolean that indicates whether the speed affects the pitch or not.
Add a minimum seek speed to EngineBufferScaleRubberBand. Workaround for Bug #1263233.
Add a last-ditch effort workaround for Bug #1263233 in case our workaround in 1cbbf166 fails.
Oops, fix last-ditch workaround to work going backwards.
Get rid of log messages on resize. Fixes Bug #1263484.
Add support for 'ppc' and 'ppc64' as valid machine types.
Prevent some master sync party-stoppers:
* Deck passthrough activates -> sync disables
* Track ejected -> if master, sync disables, otherwise no change.
* Beatgrid on track cleared or becomes empty (0BPM) -> if quantize enabled, disable it (that's all we can do from bpmcontrol)
Prevent another party stopper
* If track is loaded or unloaded on explicit master, hand off.