Added SessionManager_sessionStats()
Prevent startup is cjdns is already running. Closes #317.

Before startup, it tries to ping existing cjdns instance. If ping
succeeds, cjdroute refuses to start.
Better names for ping-related variables.
Added sessionStats python script, fixed SessionManager_getHandles() to report correct handle numbers.
Merge branch 'startup-check' of https://github.com/m1kc/cjdns into next
fixed a crash-on-start bug caused by a leftover UDP socket.
added parameter to allow changing timeout for adminClient, set timeouf to 100ms for checking if cjdns is active already.
Added ARM NEON build
2 minor fixups for NEON build
Updated CNaCl build to fix ARM NEON issue
further NEON cleanup
Allocator should not disconnect until freeing is complete. This will improve performance of freeing operation.
Fixed NodeStore logic surrounding broken and stale paths.
Merge branch 'master' into next
Too many searches causes OOM condition.
Added announcement of switch encoding schemes and made nodestore not allow any new nodes unless they are behind a direct peer.
New version of cnacl which makes inttypes not check for signed int wrapping.
Need to flush peers when they become unresponsive!