Collection of changes (mostly to db source)

- Replaced string malloc()... calls with strmemcpy() from strext.h where appropriate
- Added table name to column struct (useful for WHERE's)
- Changed the column type enum to powers of 2 (potential for NULLABLE flag  by or'ing)
- Added last_qry and num_queries to connection struct
- Fixed destruct tables stopping on error
- Renamed owners to users except in the meta table
- Fixed the 'tableExists' query

src/db_connection.h

@@ -13,6 +13,12 @@ struct stored_conn_t {
 
   void *conn;
 
+  char *last_qry;
+  size_t last_qry_len;
+  size_t last_qry_alloc;
+
+  uint32_t num_queries;
+
   uint8_t isOpen        :1;
   uint8_t inTransaction :1;
   uint8_t needsReset    :1;