simple parsing of keyboard event file input

Signed-off-by: Leo Bärring <leo.barring@gmail.com>
perhaps halfway to a proof of concept

works as intended so far in a standard xterm and
e.g. sudo ./gritty -- /bin/bash -i, however on the
target platform (arduino yun (running openwrt))
there are problems with typed characters and $PS1
not being printed. The exact culprit is yet to be
identified.

Signed-off-by: Leo Bärring <leo.barring@gmail.com>