Implement the block scalar scanner.
Implement the block scalar scanner.

git-svn-id: 0565f6b8fb3ed376b18cfb8d5c241ae1d78d7d63@189 18f92427-320e-0410-9341-c67f048884a3

yamad/libyaml,kylewlacy/libyaml,ingydotnet/libyaml-mirror,yamad/libyaml,Distrotech/yaml,Distrotech/yaml