def <<(filename)
      if File.directory?(filename)
        Dir.foreach(filename) do |x|
          self << File.join(filename, x) unless x.start_with?('.')
        end
      elsif TDP.patch_file?(filename)
        @patches << Patch.new(filename)
      end
    end
def <<(filename)
      if File.directory?(filename)
        Dir.foreach(filename) do |x|
          self << File.join(filename, x) unless x.start_with?('.')
        end
      elsif TDP.patch_file?(filename)
        @patches << Patch.new(filename)
      end
    end
Creates a new Engine object.

 db :: must be one of:
 * instance of Sequel::Database class
 * database URL that can be passed to Sequel.connect()


 Registers patch files in the engine.

 filename :: may be either a name of .sql file or a name
 of directory (which would be recursively scanned for .sql
 files)