added burndown for taskboard

- taskboard-column: added type to mark as column with cards to calculate burndown
- taskboard: added burndown-table to track sprint-burndown of taskboard with dates/capacity/slack and PO & team commitment
- taskboard: added burnhours-table to track burned hours of taskboard with date
reformatting only (replaced TABS with spaces)
added burndown to track sprint-burndown of taskboard

- taskboard: added action-dialog in action-bar to 'Setup Burndown' with dates/burndown-columns/capacity/slack and PO & team commitment
- taskboard-burndown: load and update burndown data
- taskboard-burndown: renamed db-table 'burndown' to 'initburndown'

- taskboard-column: renamed type to mark as column with cards to calculate burndown 'type' to 'coltype' as 'type' is reserved column-name

- taskboard: added convenience function to send success-message
updates taskboard after updating setup of init-burndown
taskboard-burndown: check, parse, complete and re-format burndown-dates

- taskboard-burndown: widen input-field for burndown-dates
update taskboard burned-hours if moving cards with hours from burndown-columns for current date

- taskboard-burndown: update taskboard burned-hours when moving cards for burndown-columns marked with coltype=1
  - on moving cards from/to burndown-columns
  - on removing cards
  - on copying cards
extend taskboard: add dialog to fix burndown-hours for dates of taskboard

- taskboard-burndown: allow init- & fix-burndown only for editors
- taskboard: added action-dialog to add/substract hours for dates in burndown
extend taskboard-burndown: added due-time, which is normally time of daily-meeting

- taskboard-burndown: book burned-hours on next day if due-time is reached, default 13:00
- taskboard-burndown: keep sprint-dates sorted
- taskboard-burndown: added field in db-table initburndowns.duetime

- bugfixes find_in_array(), minor text-changes
taskboard-burndown: replaced original taskboard-burndown with new larger burndown-diagram showing burned-hours

- taskboard: show new larger burndown-diagram with lines & text representing Hours/PO-Commit/Team-Commit/Slack/Velocity for each day
- taskboard-burndown: commented out ogirinal burndown-chart
added axis-values for taskboard-burndown diagram, using gradient white-greyish background

- updated plotting library jquery-flot 0.5 to 0.6
taskboard-burndown diagram: added x-axis time-ticks only up to last booked hours of todays time

- taskboard-burndown diagram: correct team & PO commitment from capacity, adjust velocity
- taskboard: removed card-specific burndown-diagram by commenting out
taskboard-burndown: added velocity for sprint-burndown

- taskboard: enter velocity in setup burndown-action-dialog
- taskboard: use velocity in burndown-diagram replacing default 50% velocity
- taskboard: added db-table-field 'initburndowns.velocity'