New cursor management
Merged master
New ranges management

-Range calculation now uses Logics.accessible_positions
-Cursor is now restricted to range
-Added debug functions and exception handling to Path
-Added a type alias to Logics (for easier manipulation)
Tests with main menu
Merge branch 'master' into new_ranges
Merge pull request #73 from GL-MPRI-2014/new_ranges

La branche est stable, et j'ai besoin d'un fix sur master.