Added Target Dates to Burnup/Burndown charts

The feature allows to set a date as a target date. The chart will show Target Dates as vertical lines:

Introduced lazy loading

Revisited approach to chart data upload. In a nutshell, some data is cached and can be rendered faster. Now the chart shows each piece of data once it arrives. As a result the user can start working with chart before all data loaded.

Add JQL filter input to Forecast tab for Burnup & Burndown charts

Enables to see the projection of the finish date for a custom scope defined by JQL expression. The chart automatically updates as the progress and the scope changes.