fix rendezvous class semantics

[Fred T. Hamster]

fix rendezvous:

1. the rendezvous on linux still uses that hateful file for the lock. that needs to be re-addressed or redressed or dressed up in lace or whatever to fix it.
2. the shared memory chunks don't automatically get cleaned up, especially if ctrl break is hit. this is bad.
3. it means the program never gets it right ever again. what we need to do is figure out how to make this stuff right.
4. we can't do a simple file, since those get left behind and the non-existence of the file can trigger thinking the app is gone.
5. it's silly that there's no sync capability like this. crap.
6. but at least get rid of the approach of using shm_open. that just doesn't work right and the files can't even be cleaned up.