Preprocessing includes building the InputSpace, checking the input dimensions and assigning the inputs to parameters.

Some surrogate strategies and PostProcessing options need to be reworked

Tested static training with PCE on analytical example, remaining changes tbd for sequential training and postprocessing

Initial split of the classes, MetaModel contains empty or general functions, PCE adds PCE/aPC specific options.
Training tested with User-guide example

Reduced the number of samples, walkers, etc for BMC for this example, so that the pipeline can run without exceeding the time limit

Changed the training samples and added BayesInf and additional models for BMC

Finished the example for BayesInf for the user guide and fixed some small bugs for MCMC with a single input.
Started working on the user guide for BMC, but issue in AL with changes in the model

All combinations of tradeoff-exploration-exploitation run through with SeqDesign. Reverted BayesInf to the current develop branch

example_analytical_function_testSequential runs through all the sequential options and contains notes on which do not work.
Choose_next sample now uses only one set of candidate samples

User guide startet for models, surrogate training, sequential training, postprocessing and BAyesian classes. The guide now contains simplified UMLs (for BayesInf not yet done).

Webpage includes quickstart, user guide, tutorial, example collection and api.
One new example was added for the user guide.

An example 'principal_component_analysis' was added to specifically test this functionality. It uses the analytical model.
Fixed two if-calls in `pca_transformation` to match older code and the content of the function.