* magit.el (magit-insert-region, magit-insert-current-line): New.
(magit-insert-hunk-item-region-patch): New.
(magit-run*): Added 'input' parameter.
(magit-run-with-input): New.
(magit-diff-item-insert-header, magit-insert-diff-item-patch,
magit-insert-hunk-item-patch, magit-apply-diff-item): Rewritten to
use *magit-tmp* buffer instead of a file.
(magit-apply-hunk-item): Likewise, and also restrict the patch to the
region when appropriate.
(magit-discard-item): Make sure that diff items that are not in the
staged or unstaged sections can not be discarded.
* magit.texi: Document it all.
