This patch adjusts the various users of the 'Child' API to the changes
on the account of the new non-blocking parent interface. It also removes
the use of the no-longer-available 'Connection::KEEP_OPEN' feature.
With the adjustment, we took the opportunity to redesign several
components to fit the non-blocking execution model much better, in
particular the demo applications.
Issue #2120
* Supply Env to Input::Session_component
* Attach input event dataspace at Input::Client
* Process input events by lambda rather than pointer
* Supply Env and a label to Input::Connection
* Wm serves valid input_session to decorator
* Per-source signal handling at input_merger
* Base API update for dummy_input_drv, test_input
* Input API update for launcher, menu_view, terminal,
mupdf, sdl, seoul, virtualbox
Ref #1987
The main feature for this version upgrade is the use of the instruction
emulator (IEM) to speed up execution and less often the slow recompiler.
issue #2059
