launch_daemon: give the main worker thread a different name.

* It's now called "main worker" instead of just worker.

launch_daemon: Increased the number of worker threads.

* Since we're disk bound, and not CPU bound, it doesn't make much sense
to restrict the number of threads on the number of CPUs.
* It's still not completely independent of the number of CPUs now,
though: we'll have 3 * CPU count worker threads.

launch_daemon: Fixed a race condition in Worker startup.

* When the thread is started during the construction of the base
class, the virtual method table may still point to the methods
of the base class when the thread actually starts to run.
* This caused the main worker to have a timeout, which could
eventually be reached which in turn caused all job processing
to stop.
* That's what you get when you do Java all day; whoever designed
C++ should be slapped (I'm talking to you, Bjarne).

launch_daemon: log failed launch jobs.

launch_daemon: Moved (Main)Worker to its own file.

launch_daemon: Fixed a race condition in Worker startup.

* When the thread is started during the construction of the base
class, the virtual method table may still point to the methods
of the base class when the thread actually starts to run.
* This caused the main worker to have a timeout, which could
eventually be reached which in turn caused all job processing
to stop.
* That's what you get when you do Java all day; whoever designed
C++ should be slapped (I'm talking to you, Bjarne).

launch_daemon: log failed launch jobs.

launch_daemon: Moved (Main)Worker to its own file.