Topic/asio appclock

boost.asio is not only about networking, but about asynchronous IO in general. this patch greatly simplifies the terminal client by using an ioservice for the appclock. especially boost.asio handles all platform-specifics internally.

jakob, could you review the qtcollider-specific part? especially, i'm not sure if the timer-related part isn't better off, staying in qt's event loop.