* reassert lock on pidfile during pidfile_write
The documented usage of pidfile_open and pidfile_write did not actually work
because the flock on the pidfile would not survive the daemonize call to fork
to a background process. Now we re-assert the lock on the pidfile when calling
pidfile_write (aborting if the lock cannot be obtained) so that the pidfile can
be reliably used as a lockfile as documented.
* Updated build instructions for Debian.
* Corrected unclear pidfile_open documentation.
* manual page rendering improvements.
* Update README and license and remove superfluous stuff from launcher.h
* Support for Tcl 8.6
* In pid_open properly handle the case of specifying the path to the pid
file. Also properly support the file mode argument.
