Start work on dot management script
Add error handling
Add function to list available groups
Be explicit about the error messages

Prefixes all error messages with 'Error: '
Add set and clear groups functions
Setup basic build tree function to setup the files

This doesn't do anything yet except call the compile-tree function
Handle basic dotfile building

This doesn't yet handle overriding files or extending files
Save groups config file to $XDG_CACHE_HOME
Handle override files