Wesnoth 1.18.1

@Alert: Stable releases 1.18.1 has been released! This is the first update for the 1.18 stable release series, which means it has a number of fixes for issues found since the release of 1.18.0 (many of which have already been mentioned in the 1.19.0 release announcement):

• a button has been added to the build info dialog to allow re-running the migrator against previous versions.
• the language selection dialog has been overhauled to provide more information directly as well as to have links to more information about translations and their completeness.
• the campaign story screen has been redesigned with new, updated graphics and appearance.
• an annoying bug that would cause messages to sometimes be instantly dismissed has been fixed.
• watching a replay where an achievement is accomplished no longer completes that achievement for the person watching the replay.
• unit portraits in the in-game help are no longer way too large when the pixel multiplier is set to a value larger than one As usual, for more details see https://r.wesnoth.org/t58371