(hif-end-of-line): New function.

(hif-end-of-line): New function.
(hide-ifdef-mode): Set line-move-ignore-invisible.
(hide-ifdef-region-internal): New function.
(hide-ifdef-region): Use it.
(hif-defined): Return an integer.
(hif-infix-to-prefix): Remove.
(hif-tokenize): Parse from the buffer rather than from a string.
Correctly tokenize integers.  Use forward-comment.
(hif-expr): Use hif-or.
(hif-term): Use hif-and.
(hif-factor): Use hif-not.  Handle numbers properly.
Don't require parenthesis around `defined's argument.
(hif-and, hif-or, hif-not): New funs.
(hif-canonicalize): Pass a region to hif-tokenize.  Use hif-not.
(hif-hide-line): Don't hide the \n before the line.
(hif-possibly-hide): Correctly handle numeric evaluation results.