1) Remove any floatval() casting. They are breaking / killing
.10 versions (converting them to .1). Since Moodle 2.0 all the
backup::RELEASE have been 100% numerical values.
2) Use version_compare() always to compare backup::RELEASE values.
They are always versions and the function is aware of versions
> .9, able to clean/ignore alpha chars... and everything else.
Note that I've also changed a couple of cases in formats (topics and
weeks) that were correct, but just added the same comment and used
the same version_compare() comparison parameters style, so all uses
in core are consistent (and safe to be copied out there).
Eloy Lafuente (stronk7)