Typo fix

In addition to the string "@I" as identifier to replace by the name of instance service,
the following identifier are now recognize :
@I, @U, @u, @G, @g, @H, @S, @R. see doc/66-identifier.md for furthers information.

These directories is used to properly define environment variable
at start of a scandir

This reverts commit 87bd69c6.

to internal version_compare and version_store respectively.