replace calendar method to faster version

lib/tdiary/io/default.rb

@@ -218,20 +218,6 @@ def transaction( date )
 			end
 
 			def calendar
-				calendar = {}
-				Dir["#{@data_path}????"].sort.each do |dir|
-					next unless %r[/\d{4}$] =~ dir
-					Dir["#{dir.untaint}/??????.td2"].sort.each do |file|
-						year, month = file.scan( %r[/(\d{4})(\d\d)\.td2$] )[0]
-						next unless year
-						calendar[year] = [] unless calendar[year]
-						calendar[year] << month
-					end
-				end
-				calendar
-			end
-
-			def calendar2
 				calendar = {}
 				Dir["#{@data_path}????/??????.td2"].sort.each do |file|
 					if file =~ /(\d{4})(\d{2})\.td2$/