Changes

distances: allow internal restrict before having the distances struct
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

distances: allow internal distances with NULL objects
Immediately restrict the arrays if needed.
Useful when nodes are ignored after being added to the array of nodes
in the Linux/sysfsnode backend.
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

common-ps: handle filtering by name inside the common ps API
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

utils/hwloc-ps: add --json-server
Open a socket, listen to incoming requests in a loop, and reply with
procs/threads information as JSON on a socket.
Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

contrib: add hwloc-ps.www to display bound processes/threads in an
interactive webpage
This requires:
* hwloc-ps --json-server on the target machine
* nodejs running on local machine See contrib/hwloc-ps.www/README for
details.
This also serves as a real-world example of playing with the lstopo
nativesvg backend.
Refs #54
Signed-off-by: Valentin Hoyet <Valentin.Hoyet@inria.fr> Signed-off-by:
Brice Goglin <Brice.Goglin@inria.fr>