Automatic default and latest symbolic versions

When the implicit default mechanism and the advanced module version specifiers are both enabled, a default and a latest symbolic versions are automatically defined for each module name.

This new feature gives the ability to select the highest version available for a module, without knowing beforehand this version name:

$ module load -v foo@latest
Loading foo/1.10

The symbolic versions are automatically defined unless a symbolic version, an alias or a regular module version already exists for these default or latest version names.