* Move wctime, mtime, etime types to ddsrt
* Add ddsrt_time_wallclock
* Change ddsrt_time_monontic, elapsed to use mtime, etime types
* Remove now, now_mt, now_et
* Rename X_to_sec_usec to ddsrt_X_to_sec_usec
* add_duration_to_X to ddsrt_X_add_duration (to be in line with the
existing ddsrt_time_add_duration)
* elimination of ddsrt/timeconv.h, it added more in the way of
complications than it did in making things more elegant
* rename of q_time.[ch] to ddsi_time.[ch]: that now only deals with DDSI
timestamps and durations on the wire
Signed-off-by: Erik Boasson <eb@ilities.com>