Making the user/ path more useful.

- Enhanced the filename detection and parsing for the ERB templates.
  Should result in better (more accurate) dependencies.
- Moved dependencies for config/ssh-config to user/ instead of ~/.
- Added helper methods for user paths and platform paths.
- Made it so that include file paths could be directory patterns.
- Added a {FILE} pattern to match the basename of the current config
  file we are processing.
- Made some methods consistent.
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