Adapt version modulefile, which is deployed in versioning installation
mode, to re-initialize module command during its unload, to restore the
command of the previously loaded version.
Goes through a full re-initialization to overcome incompatible
definition of the module command between version 3 and 4.
This full re-initialization cannot be attempted on scripting shells,
like Perl or Python, as function re-definition is not a common practice
on these languages.
When --enable-versioning is set at configure time, deploy the setup of
the MODULE_VERSION and MODULE_VERSION_STACK environment variables in
modulecmd.tcl and in a version-specific modulefile.
This version-specific modulefile is deployed in a @baseprefix@/versions
modulepath directory, which is also created specifically for versioning
installation mode.
MODULE_VERSION and MODULE_VERSION_STACK environment variables setup in
modulecmd.tcl is commented if versioning installation mode is not
enabled rather deleted to guaranty consistency across code coverage
tests (same code line numbering whatever the installation options set).
version-specific modulefile is a bit different than the one used before
<4.0 as now module version is initialized when loading this module by
calling the autoinit action on the modulecmd.tcl script.
These version-specific modulefiles enable to switch from one module
version to another but there is an incompatibility of initialization
between Modules 3.2 and Modules >=4. Switching from Modules 3.2 to
Modules >4 will be possible, but not going back from >4 to version 3.2.
