Remove psgml and xml support

I don't use.  Trying to trim .emacs
Remove cl load from modes.el

Already required in init.el
Comment and spacing changes
Remove ess shift-enter keybinding

No need. Use C-enter as in default ess. And C-up and C-down are already
bound in comint mode to previous and next history commands.
Use K&R C coding style, remove custom style

No need for custom style. Trying to simplify things.
Move C mode key definitions to ekeys.el