Upgrading mchview with new features :

Upgrading mchview with new features :

- adding Status and StatusMap as possible sources (from OCDB)
- adding one convenience computed dimension for the Gains (=1/a1/0.2 in mV/fC)
- adding --de and --chamber options to start the display on a given part of the detector, instead of the global view of all the chambers
- chamberId in the text label is now starting at 1, to avoid confusing (as anywhere else we're used to start at 1 when naming those chambers)

Also fix a bug for the contour computation (AliMUONContourMaker), and reorganized it a bit (AliMUONContourHandler, AliMUONPainterHelper)