Setup actuation function class structure

Restructure the current actuation.py with two main classes: an actuation measurement class and an actuation model class.

The model class should

• take an ini file
• build the actuation model
• generate all intermediate data products
• contain the MCMC and GPR model functions that are used by those

The measurement class should

• take the model class and measurement data
• generate the output used for MCMC and GPR by manipulating the measurement data as described in the subway diagram