Fixed normal exit code

When an Erlang side requested termination of a process, the linked processes
got a crash signal. Now the crash is only propagated through links if
it wasn't initiated by the call to exec:stop(Pid).
Fixed bug in {append, File} option
Merge branch 'master' of git://github.com/saleyn/erlexec

Conflicts:
	c_src/exec.cpp
Merge branch 'master' into make_mac_compile_hack