Commit 85b78dda (src: Select the data inserted by `!` and `<a-!>`,
merged on 2021-03-06) broke autorestore by making it delete the
restored content. I've been using it for 6 months but never noticed
since I didn't use autorestore
Reproducer:
HOME=$PWD kak -s foo README.asciidoc -e 'exec iUNSAVED-CONTENT'
# In another terminal:
ps aux | awk '/kak -s foo/ {print $2; exit}' | xargs kill -HUP
HOME=$PWD kak -s foo README.asciidoc
Delete the trailing newline instead of the restored content.
While at it, remove some <space> commands from execute-keys, to make
it work on the breaking-cleanups branch which swaps <space> and ",".
Closes#4335
