add interface templates for HaralickOps
add interface templates for GeometricStatOps
add interface templates for FirstOrderStatOps
add interface templates for FirstOrderStatIRTOps

Interfaces marking of FirstOrderStatistics as OutputFunctions from
Iterableto RealType
add interface templates for HaralickFeatures

interfaces for implementations of HaralickOps as Features
add interface templates for GeometricFeatures

interfaces for implementations of GeometricStatOps as Features
add interface templates for FirstOrderFeatures

interfaces for implementations of FirstOrderStatOps as Features
Introduce infrastructure for first version of feature framework

Using the feature framework, one can easily compile sets of features as
updateable functions. Compiling in this case means, that all dependencies
of features to other features and/or operations are automatically resolved
if possible. Additionally, the compilation process makes sure, that
features are not computed redundantly. For example the mean requires
the calculation of a sum as well as the sum itself. The sum is only
calculated once for both features.

the most important interfaces are:
* FeatureService: Takes care of compiling
* FeatureSet: Set of semantically similiar features
* Feature: Operation returning a double.
remove interface of first order statistics from ops.list

to avoid any confusion, we try to have only one interface for each
high-level functionality if possible.
update set of first order statistic features and ops

* add new implementations of features and ops
* delete old implementations
* add templates for tests
* add featureset
update set of haralick features and ops

* add new implementations of features and ops
* remove old implementations
* add templates for tests
* add featureset
add default implementations of area for iterableintervals
add FeatureSetTest

since now, the FeatureSetTest only tests if the FeatureSet can be compiled
and updated. Additionally it serves as a demonstration how to use
FeatureSets. Anyway, in the future we need to add regression tests here
ProjectCommand: Fix to run with MeanIRT
Fix import of HistogramCreate
HistogramCreate: add getter for histogram
HistogramFeatureSet: Working with getHistogram() on Histogram1d
LocalThreshold: works with MeanIRT
ProjectTest: Fix compilation error. Import correct sum.
AbstractFeatureSet: Introduce init() method.

using the init() method we can make sure, that all inputs are populated
when we run the featureset