external libraries: add missing boost.asio headers
sclang: terminal client - implement app-clock and stdin input via boost.asio

Signed-off-by: Tim Blechmann <tim@klingt.org>
sclang: terminal client - bug fixes

* avoid deadlock in sendSignal
* fix thread-safety issue with asio timer
* initialize readline only when used

Signed-off-by: Tim Blechmann <tim@klingt.org>
sclang: terminal client - ensure work

Signed-off-by: Tim Blechmann <tim@klingt.org>
qtcollider: languageclient - use qt's timer for appclock ticks

Signed-off-by: Tim Blechmann <tim@klingt.org>
qtcollider: cancel timer if no work has to be done

Signed-off-by: Tim Blechmann <tim@klingt.org>
Merge pull request #940 from timblechmann/topic/asio_appclock

Topic/asio appclock