Fixed Highstock issue with wrong up day calculation in OHLC and candlestick. Reverts the fix for #1395. After discussion among our users, there seems to be a consensus that an up day is a day where the close value is higher than the open value. As opposed to a day where the close value is higher than the previous trade day's close value. The functionality is now reverted to what it was before. Closes #1489.