Replaced macros `rst-iterate-leftmost-...` by new function
`rst-apply-indented-blocks`. Refactored `rst-enumerate-region`,
`rst-bullet-list-region` and `rst-line-block-region` to use
`rst-apply-indented-blocks`.
Improved `rst-enumerate-region` and `rst-bullet-list-region` to not
indent empty lines and not indent lines before indented block.
Debugged those commands to not run into endless loops on blocks at the
end of a buffer missing a final newline.
Improved `rst-line-block-region` to not kill indentation.
git-svn-id: http://svn.code.sf.net/p/docutils/code/trunk@7931 929543f6-e4f2-0310-98a6-ba3bd3dd1d04