Several Corrections

The release contains bug fixes for the LangevinEstimation class:

• The attributes drift_model and diffusion_model were missing.
• The error if the noise level or the transition marker were not given is fixed.
• The documenation is adapted.

The release contains bug fixes for the CPSegmentFit class:

• The print output is adapted.
• The division by zero error for some normalizing_Z_factor values is fixed.
• The sometimes unstable integration via the Simpson rule is complemented with the simple summation of values.