Add the "PRAGMA reset_database=ON|OFF" command. When on, it causes the

database to appear to be empty, causing the next transaction to reset it to
an empty database.

FossilOrigin-Name: 02e1a13c1f04bb72599b98f51240c78d0d050de264fef5808fd97db3f4c16dac

src/sqliteInt.h

@@ -1506,6 +1506,7 @@ struct sqlite3 {
 #define SQLITE_Fts3Tokenizer  0x00400000  /* Enable fts3_tokenizer(2) */
 #define SQLITE_EnableQPSG     0x00800000  /* Query Planner Stability Guarantee*/
 #define SQLITE_TriggerEQP     0x01000000  /* Show trigger EXPLAIN QUERY PLAN */
+#define SQLITE_ResetDatabase  0x02000000  /* Reset the database */
 
 /* Flags used only if debugging */
 #ifdef SQLITE_DEBUG