pterm now uses the new uxsel module, so it's one step closer to

pterm now uses the new uxsel module, so it's one step closer to
being able to be a PuTTY as well as a pterm. In the process I've
also moved icky things like actually reading from the pty fd and
printing the `terminated on signal' messages into pty.c where they
obviously should have been in the first place. Also there's been one
interesting repercussion in the terminal code: terminal.c's
from_backend now calls term_out() directly rather than expecting the
front end to call it afterwards. This has had the entertaining side
effect of fixing a Windows-specific bug whereby activity in a port
forwarding through a PuTTY with a blinking cursor caused the cursor
to blink to ON (!!!!). So, a surprisingly far-reaching checkin as it
turns out...

[originally from svn r3017]