Keywords, Status added.
pabbrev-mode now sets inhibit-modification-hooks

This was motivated by a nasty interaction with linked-buffer
but should be general.
Improved keyboard handling.

Although not really deliberately done, effectively pabbrev had become
hard-coded to tab. This commit enables changing the keybinding, but
has to add specific support for tab and return.
Add cider-nrepl mode to ignored.
Whitespace cleanup!