Use input_context in editmap.cpp

Use the sequence "timeout(BLINK_SPEED);handle_input();timeout(-1);" all the time, instead of avoid reseting the timeout at the end of the loop.

More documentation for input_context::get_direction
Use input_context in editmap::edit_ter

Conflicts:
	data/raw/keybindings.json
use input_context in editmap::edit_trp
remove unused member editmap::lastop
fix bug: allow selecting the first terrain/furniture in editmap when moving "up".