added topolgy methods to Geometry, implemented utility classes for topology
added first implementation of AVL tree
added support for equivalence classes; getters smallest and largest
implemented leftNeighbour and rightNeighbour
support invocation specific compartor function in leftNeighbour and rightNeighbour
additional test cases close to the intended usage of AvlTree
changed signature of invocation specific "compare" function
created library 'avl_tree'
first version of line intersection algorithm
implemented first version of Bentley-Ottman-Algorithm for line intersection
fixed two problems
added .gitignore
switched back to avl_tree from  pub.dartlang.org
implemented handling of overlapping line segments
implemented isSimple on LineStrings
tested and fixed isSimple on LineString and LinearRing
optimizing isSimple checks on Line and LinearRing
Merge branch 'line-intersection' into work