Fix condition not matching documentation

The condition on child was inverted, so that Daemonize(true) was NOT
resetting the variable, contrary to what the documentation states.
Add standard output/error capturing capability

Capturing capability was added for standard output and standard error,
upon request. Even though the original Daemonize() function was kept, to
avoid changing the API, it's use is discouraged in favor of the new
MakeDaemon() (which Daemonize() internally calls). The new function uses
a structured type for parameters, that allow for non-disruptive future
addition of extra options. This reflects the use of process attributes
at os.StartProcess(), for instance.

The old child parameter is now ignored. It's effect was broader than
what was stated in the documentation (resetting an environment
variable). In fact, it was conceived to avoid further forks AFTER the
current Daemonize() call, in case a third process spawned from the child
(with os.StartProcess()) wanted to daemonize also. That is, a process
spawned from a daemon would avoid the double-fork technique when trying
itself to Daemonize(). But, if that very same program is started from a
non-Daemonize()-d process, then it would daemonize as usual.

This was a trick we once may have required at VividCortex, but is now
useless. And it's also the wrong place to do it, cause it depends on
the spawned process having received a copy of the environment, which
doesn't need to be the case. So it's better to take that off sooner than
later.

Besides the capturing capability, this fix also reserves the first three
descriptors, opening /dev/null unless there's a better choice (i.e.,
unless capturing is required for the output and error streams). This
prevents the daemon from opening another file, socket, or whatever in
FDs that are ultimately used for os.Stdin, os.Stdout and os.Stderr.
Otherwise, data written to the outputs can give unexpected results if
other resource shares the FD.

Closes #2.
Fix two spelling errors in comments
Merge pull request #3 from VividCortex/issues/2-stdout-stderr

Add standard output/error capturing capability