* etc/NEWS: Document changes.
* lisp/eshell/em-hist.el (eshell-input-filter): Set value to function
symbol. Change type to a radio for choosing functions. Refer to both
new functions.
(eshell-input-filter-default): New function. Same body as the previous
value of eshell-input-filter.
(eshell-input-filter-initial-space): New function.