Periodic merge with OT
New fetures:
- fixed small bug in CMakeLists for compilation in "supervisor" mode
- added non linear fit to gain curve: ToT = a + bx + c x^2 + d ln(x), where x is the charge in VCal. The new gain description describes much better the data especially in the low charge range (< 2000 electrons)
- "Physics" can now update histograms while running even in "supervisor" mode