Completion: Allow spaces in some fields

Completion: Allow spaces in some fields

Org has a number of places where the value read by completing-read may
contains spaces.  For these occasions, the space character needs to be
a normal character.

The recent support for ido.el invalidated these special cases because
ido has its own way of dealing with spaces.

This commit now makes sure that ido is off for the critical cases
where completion must allow spaces.