No longer depends on speedbspec for byte compile.

No longer depends on speedbspec for byte compile.
(Info-speedbar-key-map) New key map.
(Info-install-speedbar-variables) New function.
(Info-speedbar-menu-items) Update to new functions.
Install speedbar keymap only when speedbar is loaded.
(Info-speedbar-browser) New command.
(Info-speedbar-hierarchy-buttons, Info-speedbar-goto-node,
Info-speedbar-expand-node, Info-speedbar-fetch-file-nodes) New function
(Info-speedbar-buttons) Handle new node button commands.