Add adaptive-wrap-mode

This is nice in visual-line-mode e.g. when editing Markdown bulleted
lists and such.
Add yaml-mode
Preserve indentation in org-mode code blocks

This got annoying when I had pasted some Python into one.
Convert some things from macros into functions

These never needed to be macros as far as I can see.  (Though maybe
I'm wrong about modifying keymaps?)