Automate the life cycle, making the code safer.

Replaces "m_title" and "m_props".  More bloat removed.

Reduce bloat.

Reduce bloat.

There is no use in duplicating these containers.  It only means that
we have to search both, duplicating the code.

Don't fail silently.

Call titleToPathElt() only once for each object.

We need this only for path names.

Not necessary, not worth the check.

Contrary to setTerminateAndWait()'s documentation, the method does
wait for worker threads to exit via pthread_join().

Reduce bloat further.

Reduce bloat.

The update thread should not affect the rest of the system, therefore
set "idle" priority, and let it only run when nobody else is using the
resources.

The name "spt" didn't make much sense for this plugin.

Initializing and closing the Shine library without
writing any data results in a segmentation fault.
The current workaround writes zeroes if there was
no actual data.

The method emplace() was added in gcc 4.8.  This commit restores
compatibility with gcc 4.7.

Replaces the bloated std::map.

"upnp:class" is an element, not an attribute of element "item".  This
fixes a regression from commit 65ebfb16

Now writes to the de-interleaved buffers directly,
instead of writing to an intermediate fifo buffer.

Fix indentation and 80 char width lines.