use timeouts_ prefix instead of timer_, which is in the POSIX namespace (they get all the good prefixes!
clean timerNN targets
add invariant assertion code, and comment our source a little better (this really needs a formal description)
fix some comments
switch to TAILQs which have less branching logic, and because FreeBSD dropped CIRCLEQs altogether
fix timeout calculations comment
refactor API, moving struct timeout to header, renaming some routines, and adding others
rename timer.[ch] to timeout.[ch]
fix remaining internal spelling from timer to timeout
fix typo in Makefile