LONDON (Reuters) - Crypto analysts are split on whether bitcoin's rise this year is driven by unique factors or is just its latest bout of volatility. But many agree on one factor: an upcoming cut to the supply of bitcoin. Bitcoin has soared by almost half this year, to more than $10,000 (£7,675.2), for the first time since October. On Tuesday it hit its highest in five months. The cryptocurrency's 11-year history is replete with fast ascents and equally rapid plunges. In late 2017, it rose..