Start preparing Akonadi server for yet another way to launch agents.
To make it easy to switch between running agents in the AgentServer, i.e. threaded, and running them in their own process (in case of unstable agents), we'll use the agent_launcher helper program soon. This will do practically the same as the AgentServer, but only running one Agent. This approach prevents AgentWriters to have to provide a plugin *and* an executable. svn path=/branches/work/akonadi-agentserver/; revision=1181544