Major Changes in 51.rc:
* Improve drag and drop behavior on the Month view. You can now drop events
  on top of other events.
* More keyboard navigation improvements in the Month view.
  When an event is focused, pressing Ctrl+Tab focuses the month cell behind it.
  When a month cell is focused, pressing Shift+Tab focuses the first event
  in front of it.
* Fix a rare crash in the Month view when scrolling
* Be a little more permissive with the headers of remote iCalendar files.
  Files with LF line breaks are now accepted. These files are not technically
  compliant with RFC 5545, but some files are formatted like this in the wild
  and other calendaring applications accept them without problem.
* Fix event popover showing outside the window when the left mouse button is
  released outside the window
* Fix inverted Ctrl+Scroll zoom direction in the Week view
* Updated translations