Preferred mount selection for bots

Added a new table to store user-specified mount ids.
Can specify flying and ground mounts for a character which will prioritise that mount. If multiple entries, a random entry will be selected from that list.

Currently no way to add entries other than manual DB editing, but can be developed into a whisper command pretty easily.

This should gracefully fail (if no entries exist for the character, or the db table does not exist) and fallback to the default random selection as usual.

sql/playerbots/base/playerbots_preferred_mounts.sql

@@ -0,0 +1,10 @@
+DROP TABLE IF EXISTS `playerbots_preferred_mounts`;
+CREATE TABLE `playerbots_preferred_mounts` (
+  `id` INT(11) NOT NULL AUTO_INCREMENT,
+  `guid` INT(11) NOT NULL,
+  `type` TINYINT(3) NOT NULL COMMENT '0: Ground, 1: Flying',
+  `spellid` INT(11) NOT NULL,
+  PRIMARY KEY (`id`),
+  KEY `guid` (`guid`),
+  KEY `type` (`type`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8;