Indicate post-beta4 version
Add rope ladder by mrvertigo27.

Source: http://secretmaryo.org/phpBB3/viewtopic.php?f=10&t=3049&start=20#p26653

Thanks to DarkAceZ for cropping properly.
Improve ladder with @DarkAceZ’s help.
Proper names for the ladder graphics
Merge branch 'add-ladder' into release-2.0.0