Adds Random Notes (#5644)

Adds SSDocs, which manages randomly spawned documents.
    These documents can be specified in a json file or in a database.
    Adds /obj/random/document and adds /obj/random/document to the loot pool of /obj/random/loot.

Actually adding the notes to spawn is up to loredevs. If there are no notes to choose from, /obj/random/document will leave a blank sheet.

The notes can have HTML in them, meaning custom CSS and images. We're giving the loredevs a good bit of responsibility here.

SQL/migrate/V036__Docs.sql

@@ -0,0 +1,20 @@
+--
+-- Create the Documents database.
+--
+
+CREATE TABLE `ss13_documents` (
+	`id` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT,
+	`name` VARCHAR(100) NOT NULL,
+	`title` VARCHAR(26) NOT NULL,
+	`chance` FLOAT UNSIGNED NOT NULL DEFAULT '1',
+	`content` VARCHAR(3072) NOT NULL,
+	`tags` JSON NOT NULL,
+	`created_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+	`updated_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+	`deleted_at` DATETIME NULL DEFAULT NULL,
+	PRIMARY KEY (`id`),
+	UNIQUE INDEX `name` (`name`)
+)
+COLLATE='utf8_bin'
+ENGINE=InnoDB
+;