license compliance stuff and other changes

relicense to AGPLv3
comply with the MPL's file copyleft
some other changes in the direction of supporting GPT-2 which were hard to untangle from the rest of the changes (sorry)

schema.sql

@@ -0,0 +1,8 @@
+CREATE TABLE posts (
+	post_id TEXT PRIMARY KEY NOT NULL,
+	-- aka subject aka CW
+	summary TEXT,
+	content TEXT,
+	-- UTC Unix timestamp in seconds
+	published_at REAL NOT NULL
+);