Fix a typo in the ChangeLog

"Thansk" => "Thanks".
Fix multiple cancellations

After introducing ui_cancellation_reset() and updating cancellation
implementation to allow examining cancellation requests after
cancellation succeeded, menus weren't updated.

Thanks to Milan Svoboda (a.k.a. tex) for noticing.
Show "(cancelled)" notice for cancelled menus

In one of two places:
 * on status bar for empty results;
 * in menu title when there is at least one result.
Handle Ctrl-C got in kernel mode on syscall

In this case errno should be examined to determine cancellation
fact.  Also need to flag cancellation so that it can be checked
by other modules of the application later on.
Add a TODO about spacing in menu titles
Add comment for fileops:get_cancellation_suffix()