update slf4j
- remove javaproj
- less magic in ground resolution calculation
avoid unnecessary allocations and getting list items multiple times
do not recalculate constant elevation
using custom json parser for Overpass-API, not faster than xml but works also without meta-data...
scale to ground resolution at latitude, then translate to origin
... not sure if this is better though
speed up obj writing a little
fix test
add jackson json library
build with jackson