LONDON (Reuters) - Analysts have raised forecasts for the prices of European Union carbon permits through 2019 to 2021 but warned the threat of a no-deal Brexit still hangs over the market in the short term.EU Allowances (EUAs) are expected to average 26.40 euros/tonne this year and 34.37 euros/tonne in 2020, according to a survey of eight analysts polled by Reuters. The forecasts were up 8.6% percent and 6.7% percent, respectively, from prices given in April, when the projections were for..