Fix linking
Signal handling for channel cancellation
Check if any channels to cancel in the signal handler
Add sns script to manage daemons
Use environment variables

* ACHCOP to tell whether to signal parent in sns_start()/sns_die()
* SNS_IDENT to set identifier
* SNS_RUNDIR to set working directory
Stop command to signal all running sns processes
Add script function to list running/dead daemons
Add sns-trylock
Add logging daemon
Set up core dumps
Add vector and matrix message types
Redirect stderr to the sns event log
Plot vector messages
Add snsref shell command
Minor updates