Sample arbitrary filters

[codeling]

As a user, I should be able to "sample" the parameter space for arbitrary filters.

• It should be possible to specify the ranges from which to choose for each of the filters input parameters
• Various sampling methods should be available (random, uniform/cartesian grid, pseudo-random - e.g. latin hypercube, ...)

This will unify the Computation Module from Porosity Analyzer and the sampling tool from GEMSe

[codeling]

The sampling tool from GEMSE has been moved to the MetaFilters module, and it can now sample any filter from within open_iA (or external filters via a command line interface). The Computation Module has been moved to a separate FeatureAnalyzerComputation module, it will need to be split into its sampling part (which should be merged into the sampling filter now in MetaFilter) and its pipeline editor part (which should also go into MetaFilter, as a GUI for creating some textual description of a pipeline of existing filters which is then treated by open_iA as any other predefined filter).