[options] string is more explicit
Merge pull request #818 from rodo/master

Add missing option '-p' in help message
move Hilbert curve computation in compile unit
move distance computation from r-tree to element type class
move implementation details out of templat'ized container code
make rtree query do O(1) allocations only
add geometry compressor
remove potential division by zero
use explicit unsigned type in max operation
renaming file
renaming file
fixing coverity issue
moving BFS exploration into its own function
clear memory early by swap trick
cast to larger data type on 32bits, probably fixes #809
temporarily fixes #811 plus 16 others
clean up of build config
implements #801
remove dead code
partially fixes #768, #794, #812