(completion-try-completion): Change magic symbol

(completion-try-completion): Change magic symbol
property name.  Rename from minibuffer-try-completion.
(completion-all-completions): Rename from minibuffer-all-completions.
Remove hide-spaces argument.
(completion--do-completion): Rename from minibuffer--do-completion.
(minibuffer-complete-and-exit): Call just try-completion rather than
completion-try-completion to fix up the case.
(completion--try-word-completion): Try to add space or hyphen before
making `string' a prefix of `completion'.
(completion--insert-strings): Rename from minibuffer--insert-strings.