The previous commit enabling tile 'bumping' as
you move them around proved impractical with
charts that largely filled the screen.
This patch replaces this approach (original code
is retained though) by using a 'cursor' to show
where charts will be dropped / moved to and moving
or dropping to this position.
This means the layout code is complete, except for
potentially adding support for multiple layouts (e.g.
have saved layouts for different purposes like
LTM charts for last 6 months or 28 days or an
agenda view that shows past week next week calendar).
More work to support moving tiles on HomeWindow. This update
adds tile movement and 'pushing' other tiles out the way as
you move them around.
Tile ordering/positioning is still todo, but this introduces
the visual feedback during a move for the user.
