IOSource reorg.

A bunch of infrastructure work to move IOSource, IOSourceRegistry (now
iosource::Manager) and PktSrc/PktDumper code into iosource/, and over
to a plugin structure.

Other IOSources aren't touched yet, they are still in src/*.

It compiles and does something with a small trace, but that's all I've
tested so far. There are quite certainly a number of problems left, as
well as various TODOs and cleanup; and nothing's cast in stone yet.

Will continue to work on this.

src/iosource/Component.cc

@@ -0,0 +1,44 @@
+
+#include "Component.h"
+
+#include "Desc.h"
+
+using namespace iosource;
+
+Component::Component(const std::string& arg_name)
+	: plugin::Component(plugin::component::IOSOURCE)
+	{
+	name = arg_name;
+	}
+
+Component::Component(plugin::component::Type type, const std::string& arg_name)
+	: plugin::Component(type)
+	{
+	name = arg_name;
+	}
+
+Component::Component(const Component& other)
+	: plugin::Component(other)
+	{
+	name = other.name;
+	}
+
+Component::~Component()
+	{
+	}
+
+void Component::Describe(ODesc* d) const
+	{
+	plugin::Component::Describe(d);
+	d->Add(name);
+	}
+
+Component& Component::operator=(const Component& other)
+	{
+	plugin::Component::operator=(other);
+
+	if ( &other != this )
+		name = other.name;
+
+	return *this;
+	}