Fix some string issues and reveal the name of the next release (Ken Wood).

Change the tense of the Capture The Relic message, as proposed by brian (WhiteTreePaladin).
Consistently use title case for buttons.
Use more descriptive and concise option titles.
Remove two unused strings.

Fixes #4718
Refs https://wildfiregames.com/forum/index.php?/topic/22745-all-relics-captured-message/
Refs https://wildfiregames.com/forum/index.php?/topic/22461-alpha-23-name-suggestions/
Reviewed by: brian (WhiteTreePaladin), leper, GunChleoc.
Release name agreed with Itms on 2017-07-29 on irc.