How files are searched and loaded by ARC (ARgile Compiler)
==========================================================

When loading an Argile file, it is searched in directories listed in
environment variable `ARGILE_FILE_PATH' and `--add-dir' command
line option. It is searched with extension `.argl' then `.arg' then without
additional extension. Argile files maybe loaded when the `std/use' binding is
called, or they can be preloaded with `--use' command line option or with
the `ARGILE_AUTO_USE' environment variable.
If ARGILE_FILE_PATH is not set, then the following directories are used:
   /usr/include/argile/
   /usr/include/argile/argrt/
   $HOME/include/argile/
   $HOME/include/argile/argrt/
   ./