[Proposal] Running task asynchrously (+ patche)

[Jeanfrancois Arcand <jf...@apache.org>]

HI,

attached is a tentative patch that allow a Task object to run
asychronously. I have tested the patch on Solaris and win2k and
everything works fine (without breaking backward compatibility).

To use the functionality, you just have to add to a task the spawn
attribute, e.g.:

<exec dir="c:/src/jakarta-tomcat-5/build/bin/" executable="sh" spawn="true">

Since some task needs a couple of seconds to start/stop, I also added a
spawnWaitUntil attribute where you can set the time required before
moving to the next Task.

I did no wrote a <spawn> task because I think the functionality should
be available to every Task. For now I did not add the functionality to
Java, Javac, Jar.

Let me know what you think. At least I have something use when <gump>ing 
tomcat :-)

Thanks,

-- Jeanfrancois