Overhauls Custom Synthetic Code (#6803)

Loads custom synths from json or SQL as opposed to a txt file. Adds support for multiple borg sprites, ai chassis and custom ai hologram sprites as opposed to one sprite per player. Adds the ability to use custom pai sprites

SQL/migrate/V040__CustomSynths.sql

@@ -0,0 +1,16 @@
+--
+-- Create the Custom Synths database.
+--
+
+CREATE TABLE `ss13_customsynths` (
+    `synthname` VARCHAR(128) NOT NULL,
+    `synthckey` varchar(32) NOT NULL,
+    `synthicon` VARCHAR(26) NOT NULL,
+    `aichassisicon` VARCHAR(100) NOT NULL,
+    `aiholoicon` VARCHAR(100) NOT NULL,
+    `paiicon` VARCHAR(100) NOT NULL,
+    PRIMARY KEY (`synthname`),
+    CONSTRAINT `fk_ss13_custom_synths_ss13_players` FOREIGN KEY (`synthckey`) REFERENCES `ss13_player` (`ckey`) ON DELETE CASCADE ON UPDATE CASCADE
+)
+ENGINE=InnoDB
+;