[Modules] Modulefile alias and symbolic modulefile name consistency

[Xavier D. <xav...@gm...>]

Hello,

With the module-alias and module-version modulefile commands,
alternative names can be given to a modulefile. When these names are
used to load for instance a modulefile, they are resolved to the
modulefile they target which is then processed for the load action.

Until now, the alias and symbolic version names were correctly
resolved for the load and unload actions and also for the querying
sub-commands (like avail or whatis). However this alternative name
information vanishes once the modulefile it resolves to is loaded. As
a consequence there was no consistency over these alternative
designations. In the following example f modulefile declares a
conflict on e alias which resolves to d modulefile:

    $ module load e
    $ module list
    Currently Loaded Modulefiles:
     1) d
    $ module info-loaded e
    $ module load f
    $ module list
    Currently Loaded Modulefiles:
     1) d   2) f

Consistency of the alternative names set on a modulefile with
module-alias and module-version commands is now ensured to enable
modulefile commands prereq, conflict, is-loaded and module-info loaded
using these alternative designations as argument. This consistency is
achieved, like for the conflict and prereq consistencies, by keeping
track of the alternative names of the loaded modulefiles in an
environment variable called MODULES_LMALTNAME:

    $ module load e
    $ module list
    Currently Loaded Modulefiles:
     1) d
    $ module info-loaded e
    d
    $ module load f
    WARNING: f cannot be loaded due to a conflict.
    HINT: Might try "module unload e" first.
    $ module list
    Currently Loaded Modulefiles:
     1) d

This change is available in git repository and will be included into
the upcoming feature release v4.2.

Cheers,
Xavier