* calc-ext.el (calc-init-extensions): Add keybinding for 'calc-option'.

* calc-ext.el (calc-init-extensions): Add keybinding for 'calc-option'.
Add `calc-option-prefix-help' to calc-help autoloads.
(calc-inverse): Add "Option" to message, as appropriate.
(calc-hyperbolic): Add "Option" to message, as appropriate.
(calc-option, calc-is-option): New functions.

* calc-help.el (calc-full-help):  Add `calc-option-help'.
(calc-option-prefix-help): New function.

* calc-misc.el (calc-help): Add "Option" entry.

* calc.el (calc-local-var-list): Add `calc-option-flag'.
(calc-option-flag): New variable.
(calc-do): Set `calc-option-flag to nil.
(calc-set-mode-line): Add "Opt " as appropriate.