* 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