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' (separated by `:' or `;' on WIN32
platforms) 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/
   ./
