Refactoring softmenus stack code plus backup/programs version update

This is the first step in reworking the soft menu stack. There is no new functionality nor bug fix, this is just code reorganization to prepare the introduction of separate soft menu stacks for RUM, AIM and PEM: all soft menu stack management code is now located in softmenus.c to make it easier to change it.

In addition the backup/program version has been updated following the introduction of the new audio extensions.

Related to #727 (closed)