wip for db_migrations for core schema

sql/mysql/migrations/56.sql

@@ -0,0 +1,16 @@
+begin;
+
+drop table ttrss_enclosures;
+
+create table ttrss_enclosures (id serial not null primary key,
+	content_url text not null,
+	content_type varchar(250) not null,
+	post_id integer not null,
+	title text not null,
+	duration text not null,
+	index (post_id),
+	foreign key (post_id) references ttrss_entries(id) ON DELETE cascade) ENGINE=InnoDB;
+
+update ttrss_version set schema_version = 56;
+
+commit;