Better antag tracking (#5816)

This PR moves the tracking of the antagonists from the char spawn to the assignment and removal of the antag status.

It should properly account for all antags that are added/removed via the add_antagonist / remove_antagonist verbs

SQL/migrate/V034__better_antag_stats.sql

@@ -0,0 +1,23 @@
+--
+-- Adds a new table specifically for tracking antagonist assignments
+--
+
+ALTER TABLE `ss13_characters_log`
+	DROP COLUMN `special_role`;
+
+CREATE TABLE `ss13_antag_log` (
+	`id` INT(11) NOT NULL AUTO_INCREMENT,
+	`ckey` VARCHAR(32) NOT NULL,
+	`char_id` INT(11) NULL DEFAULT NULL,
+	`game_id` VARCHAR(50) NOT NULL,
+	`char_name` VARCHAR(50) NOT NULL,
+	`datetime` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+	`special_role_name` VARCHAR(50) NOT NULL,
+	`special_role_added` TIME NOT NULL,
+	`special_role_removed` TIME NULL DEFAULT NULL,
+	PRIMARY KEY (`id`),
+	INDEX `FK_ss13_antag_log_ss13_characters` (`char_id`),
+	CONSTRAINT `FK_ss13_antag_log_ss13_characters` FOREIGN KEY (`char_id`) REFERENCES `ss13_characters` (`id`) ON UPDATE CASCADE ON DELETE CASCADE
+)
+COLLATE='utf8_general_ci'
+ENGINE=InnoDB;