Set nbsp and unset eol in listchars
Ensure LineNr highlight remains after setting colorscheme
Colorscheme fixes

* Highlight overlong lines, making sure the highlight stays set after
  setting a colorscheme.
* Remove colorscheme autocommand workaround for Vim on RHEL.
* Miscellaneous refactoring.
Autoindent by default, remove obvious comments
Slight reformat of ftplugin files