- sort data on the gant diagram
- make the gantt diagram much bigger
- stop calculating the height of the gantt diagram, it
  was buggy since the tree was not fully expanded by default
- better setup of gantt diagram, use one scale for days,
  a sub scale for hours (grouped by 4)

All the display of results needs to be reviewed

bug in Machine canAcceptAndIsRequested fixed. Now exit is assigned in every occassion that true is returned