refreshMultiLine->refresh_multi_line in LineEdit
LineEdit: use dispatch in normalize_key, keymap_prepare

Also, small formatting fixes
Additional Meta-Enter mapping in ReadLine

wasn't working on Linux
REPL search: execute more movement commands

Mimicking GNU readline, arrow keys and other movement
commands get out of search mode and are executed. (This was
already done for ^A, ^E, Home and End).

Also add a binding for Meta-backspace.
Bind ^C in help/shell REPL modes

make it return to main prompt