CELL configuration directory

Quickstart/executive summary:
- CELL's own configuration files are in the CELL/ subdirectory
- create as many configuration files as you want, in whatever
  directory structure you like: CELL will walk the tree
- point CELL to the root of the tree - three options:
  1. CELL_CONFIGDIR environment variable
  2. ~/.cell/CELL.conf (SITECONF_PATH="...")
  3. /etc/sysconfig/CELL (SITECONF_PATH="...")
- CELL distinguishes four different types of configuration parameters
  by matching filenames to the following regular expressions:
  1. 'meta' ^.+_MetaConfig.pm$
  2. 'core' ^.+_Config.pm$
  3. 'site' ^.+_SiteConfig.pm$
  4. 'message' ^.+_Message(_[^_]+){0,1}.conf$
- filenames that don't match any of the above regexes will be passed
  over (ignored)

For details, refer to the CELL Localization Guide, which can be found
in the doc/ directory of the CELL source code distribution.

