menu item added to select the starting cell
the map has now an instance
when the user select the action to select a start cell, connect an event to save the next clicked pixel
method added to check if the map is ready to be exported
alert method which displays an error message
the cells are now loaded in an attribute when the map is loaded
when the start cell is set, check that it is not a water cell
empty line added
collection of pixmaps created
start cell displayed in the map
start cell saved in a settings table
export steps split in different methods
export slight reorganisation
Merge branch 'init-cell'