Pressing Alt-Enter now uses accept-and-infer-history, with the addition of using
the last executed command for inferring if pressed while the command line is
empty
As it is problematic to get the correct char for backspace and C-Backspace
based on $TERM, especially when mosh, tmux and urxvt are combined, the config
now assumes Backspace as ^? and C-Bksp as ^H. If a terminal has these swapped
(e.g. xterm), change it according to your needs.
