Detect and auto-correct camera tilt

Follow-up of !102 (merged).

It would be good to detect and automatically correct tilts.

In the configuration file, we could add a new key in the same spirit of rotation_axis_position:
tilt_correction = [auto|algo1|algo2|value] where

• auto is the default automatic tilt computation method (it's up to us to decide which one)
• algo1, algo2 refer to tilt computation methods
• value is a scalar chosen by the user