misc: require forward iterators in sequence_difference

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
coverity: fixes

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: remove unused method from HtmlMessagesRenderer

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: improve prune logic

WIP, but better than before

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>