Added Yandex.Translate service.

Closes #8 - Yandex.Translate.
Don't try to re-run translate on language change if source text is empty.
SYM,BB10: Removed automatic translation after source text changes.

Also, fixed `privateStyle.fontSizeLarge` -> `platformStyle.fontSizeLarge`.
N9: Few forgotten includes.
Removed unused declarations from Google Translate service.