Revamp inputrc file for Leopard (snippets, 3049268)

It appears that Apple has commandeered the up and down cursor keys in the new version of the Terminal in Leopard, breaking my old bindings for history-search-backward and history-search-forward. Or maybe its just the new version of Bash that ships with Leopard.

Whatever the cause, this commit re-instates the old desired behaviour, as well as setting up key combinations for word-based movement and jumping to the beginning and end of lines.

Signed-off-by: Greg Hurrell <greg@hurrell.net>