Add convenience wrapper for pragma optimize

Author: alexcwatt

lib/sqlite3/pragmas.rb

@@ -338,6 +338,14 @@ def mmap_size=(size)
       set_int_pragma "mmap_size", size
     end
 
+    def optimize(bitmask = nil)
+      if bitmask
+        set_int_pragma "optimize", bitmask
+      else
+        execute("PRAGMA optimize")
+      end
+    end
+
     def page_count
       get_int_pragma "page_count"
     end