MEDIUM: channel/stconn: Move rex/wex timer from the channel to the sedesc

These timers are related to the I/O. Thus it is logical to move them into
the SE descriptor. The patch is a bit huge but it is just a
replacement. However it is error-prone.

From the stconn or the stream, helper functions are used to get, set or
reset these timers. This simplify the timers manipulations.
12 files changed