Extract interface RangeSearcher from LayeredRangeTree
Seperate segments searching resposibilities from Polygon2D

  - create SphereSearcher interface
  - extract LRTreeSegment2DIntersectingSphereSearcher
  - extract SegmentsMidPointLRTreeRangeSearcher
  - move corresponding tests from Polygon2D to LRTreeSegment2DIntersectingSphereSearcherTest
  - modify Model2D and PolygonTask2D accordingly
Split Model2D into Model2D, package model.influence and package model.support_domain

  - A HUGE commit
  - make general interface Factory
  - extract interface SupportDomainSearcher from searchModel()
    + use composition pattern implementations of SupportDomainSearchers
      - RawSupportDomainSearcher, FilterByInfluenceDomain and VisibleSupportDomainSearchers
      - also build SupportDomainSearcherFactory
  - extract interface InfluenceRadiusMapper and its implementation
    + ArrayInfluenceDomainRadiusMapper
    + ArrayInfluenceDomainRadiusMapperFactory
  - also rename InfluenceRadCalc to InfluenceRadiusCalculator
  - modify WeakformProcessor ...  accordingly