Ensure subprocesses quit
Merge branch 'master' of goldnerlab.physics.umass.edu:timetag-tools
timetag_acquire: Remove dead output_fds
timetag_acquire: Refer to outputs via output id

In practice this is the fd of the associated output file.
photon_generator: Fix NULL in place of 0
Fix boost-iostreams library name
Merge branch 'master' of github.com:bgamari/timetag-tools