Made Feature abstract on Geometry trype
extended GeometryCollection to keep multi* geoms

Allows to preserver structure during encoding/decoding from json
implicit conversion from its to MultiLine
implicit conversion from its to MultiPoint
implicit conversion from its to MultiPolygon
JsonFeatureCollection is builder/buffer for json
Spray Json formats for Geometries and Features
GeometryCollection test
FeatureFormats tests
removed custom marshaller

don't need it anymore
add GeometryCollectionBuilder

More natural way to build GC in some cases
fix misc format and missing case