Some end-of-life tweaks for exec-port.
Added a shutdown command that terminate() sends in order to cleanly terminate exec-port.
Send a shutdown message to exec-port and wait for it to exit.
Merge branch 'master' into application_stop_fix

Conflicts:
	c_src/exec.cpp
Merge branch 'stop_child_fix' into application_stop_fix
Merge branch 'stop_child_fix' into application_stop_fix
If we have any children, check them.
while -> if, since we will hit it again in the outer loop.
Merge branch 'master' into application_stop_fix
Merge branch 'master' into application_stop_fix
Merge branch 'application_stop_fix' of git://github.com/davidw/erlexec into davidw-application_stop_fix
Minor cleanup