Prevent aw-select from marking empty buffers as modified

[bcc32]

Previously, if you had an empty, unmodified, file buffer open and invoked ace-delete-window, this would cause the buffer to be marked as modified. with-silent-modifications is perfect for this use case, where some Lisp code temporarily modifies the buffer but it shouldn't be considered a "real" modification.

[bcc32]

@abo-abo @localauthor @seagle0128 sorry for the ping. Is this package still maintained, and if not, are you looking for maintainers? (last commit was two years ago, and some recent straightforward pull requests have not been merged)