Make the mmap shared and volitile.
Don't free things that aren't malloced.
remove some debugging output
Reduce the sandbox size to 6MB.
Remove a wrong assert.

It's ok for sb->tds_current_invokes to be greater than
ctdc->ctdc_sb_max_packets as ctdc->ctdc_sb_max_packets may have been
lowered.
Implement pause.
Tidy up the sandbox management.

Centralize validation of hash bucket counts.