Improve keymap handling.

Improve keymap handling.

*
lisp/completions-highlight.el (completions-highlight-minibuffer-map-save) :
(completions-highlight-completions-map-save) : New variables to store
the maps before enabling mode.

(completions-highlight-minibuffer-map) :
(completions-highlight-completions-map) : Maps for the mode in
minibuffer and Completions.
(completions-highlight-minibuffer-bindings) :
(completions-highlight-completions-bindings) : Modified to do maps
handling using maps parent.
(completions-highlight-minibuffer-tab-through-completions) : Add call to
completions-highlight-completions-bindings.
(completions-highlight-minibuffer-bindings) : Fix name.