A long standing issue is that bindings cannot mix special input functions
and shell commands. For example,
bind x end-of-line "commandline -i x"
silently does nothing. Instead we have to do lift everything to shell commands
bind x "commandline -f end-of-line; commandline -i x"
for no good reason.
Additionally, there is a weird ordering difference between special input
functions and shell commands. Special input functions are pushed into the
the queue whereas shell commands are executed immediately.
This weird ordering means that the above "bind x" still doesn't work as
expected, because "commandline -i" is processed before "end-of-line".
Finally, this is all implemented via weird hack to allow recursive use of
a mutable reference to the reader state.
Fix all of this by processing shell commands the same as both special input
functions and regular chars. Hopefully this doesn't break anything.
Fixes#8186Fixes#10360Closes#9398
